Remember that this thread is primarily for discussing the election and the candidates, not the issues themselves (this is not to say that I disapprove of the lively debate that's going on). That said, I'll now try to point your attention to the Senate races this year.
This year's Senate races are almost the exact definition of "so close, yet so far" for the Republicans. They are only 2 seats away from controlling Congress, but now, it seems that on a terrible day, the Democrats still gain 3-4 seats. Besides the general feelings against the Republicans this year, there are other factors that culminate in an enormous disadvantage for them. For one, they are defending 23 seats this year, as opposed to 12 for the Democrats, and also, 5 incumbent Republicans are retiring, while none of the Democrats are. The following is a race-by-race analysis; when I'm stating the people involved, it will be in the format Democrat v. Republican. I'm not trying to be partisan by using that format, so don't accuse me of doing so. (I) denotes an incumbent. The states will be listed alphabetically.
Note: Be wary of early polling. While interesting, they are not a good indicator of what is to come, as politics has many unpleasant surprises. See Fossella, Vito or Allen, George Macaca.
Arkansas: Mark Pryor (I) v. None
The Republicans aren't running a candidate against Mark Pryor this year. While this may seem surprising given that Pryor is a first term senator from a state that usually votes Republican in national elections, Pryor is quite popular, and Arkansas is very Democratic at the state level. Its governor, lieutenant governor, all other state officers, both senators, and 3 out of its 4 representatives are Democrats.
Alabama: Vivian Figures v. Jeff Sessions (I)
Jeff Sessions will almost certainly coast to reelection. He is reasonably popular in very conservative Alabama, and Figures is much more liberal than the state as a whole. Recent polling by Rasmussen indicates that Sessions leads Figures by over 30%.
Alaska: Mark Begich v. Ted Stevens (I)
Normally, Ted Stevens, the longest-serving Republican senator ever, would be elected in a landslide by this very Republican state, but he's the poster boy for wasteful spending outside of Alaska ("the bridge to nowhere") and he's also in trouble with the government. This is quickly shaping up into what will probably be the national battle: change v. experience (more of the same). Polling currently puts Begich at a slight advantage over Stevens, though a week is like a year in politics. Obama has strong support in the Northwest, so while he will probably not win Alaska, he can help Begich do so.
Colorado: Mark Udall v. Bob Schaffer
An open seat in a blueing state has piqued everyone's interests. Wayne Allard kept his 1996 promise to serve only two terms, so he is retiring; he had low approval ratings anyways and was named one of the 5 worst senators by Time in 2006, so he may have been in for a tough fight anyways. Udall holds a modest lead over Schaffer in early polling, and may be helped by Obama's coattails in the Northwest. Obama also polls ahead in Colorado.
Delaware: Joe Biden (I) v. Christine O'Donnell
Joe Biden has been serving in the Senate since he was 30, which was a long, long time ago. He consistently wins by convincing margins. Christine O'Donnell looks like a cutout from Playboy. Give me a break.
Georgia: TBA v. Saxby Chambliss (I)
Saxby Chambliss ran a campaign so nasty in 2002 that even John McCain and Chuck Hagel decried it. He juxtaposed pictures of Max Cleland, a Vietnam veteran and triple amputee, with pictures of Osama bin Laden and Saddam Hussein. However, Chambliss, even with his not-so-spectacular approval ratings, has polled far ahead of all possible Democratic foes and will likely win reelection.
Idaho: Larry LaRocco v. Jim Risch
Larry Craig tried to have homosexual interaction with an undercover police officer in a Minneapolis airport's bathroom. End of Larry Craig. However, Jim Risch, Idaho's lieutenant governor, stepped in to prevent the Republicans from possibly losing what should be a very safe seat. Larry LaRocco was Idaho's last Democratic representative ever, but he doesn't have much of a chance, even if he is helped to some extent by Obama's coattails.
Illinois: Dick Durbin (I) v. Steve Sauerberg
Dick Durbin is the Senate Majority Whip. Steve Sauerberg is an unknown physician. They are in liberal Illinois. Obama will have huge coattails there. That equals safe seat.
Iowa: Tom Harkin (I) v. Christopher Reed
Tom Harkin is a bit more liberal than the Iowa mainstream, but he is the chair of the Senate Agriculture Committee, something of great interest to Iowans. Polling shows Tom Harkin 16% ahead of his challenger, Christopher Reed.
Kansas: Jim Slattery v. Pat Roberts (I)
Pat Roberts fits the Kansas conservative mold, but he isn't polling as well as he should be against Jim Slattery, a former congressman. He is only 12% ahead and barely over the 50% incumbent safety mark. Roberts is still the solid favorite, but if Slattery wins, then, Toto, I don't think we're in Kansas anymore. If Obama chooses Kathleen Sebelius as vice president, the chances for Slattery increase.
Kentucky: Bruce Lunsford v. Mitch McConnell (I)
Bruce Lunsford is a wealthy businessman, and wealthy businessmen rarely win against established elected officials. Mitch McConnell is the Senate Minority Leader, and Kentucky is a fairly conservative state. All this points to the Republican dream of having a safe seat. However, as we all know, dreams rarely come true. Rasmussen reports that Lunsford has a 5% lead over McConnell. While this is at least partially influenced by Lunsford's post-primary bump, it is alarming nonetheless.
Louisiana: Mary Landrieu (I) v. John Kennedy
Mary Landrieu is probably the only Democrat that is remotely threatened this year. Her opponent, John Kennedy, of no relation to the Kennedy political family, is polling only 3% behind her. Hurricane Katrina caused an exodus of primarily Democratic people, largely blacks, from New Orleans. However, Landrieu has been in tough situations before and survived, so she still has something of an advantage.
Maine: Tom Allen v. Susan Collins (I)
Unlike her colleague Wayne Allard, Susan Collins is not honoring her 1996 pledge to serve only 2 terms. Collins is much like Lincoln Chafee, who was voted out of Rhode Island in 2006: she is a moderate who gets better ratings from liberal than conservative groups, and national Republicans probably really don't want to support her, but they realize she's the only one who can win in Maine. In Rhode Island in 2006, party affiliation trumped personal popularity; however, Maine isn't quite as liberal as Rhode Island, so expect a huge fight here. Collins currently leads by a solid 10% margin, but Obama will likely have strong coattails in Maine, as he currently leads by 13%.
Massachusetts: John Kerry (I) v. TBA
If there is any doubt in your mind as to who is going to win, I hope you have enough money to hire a good therapist for prolonged treatment.
Michigan: Carl Levin (I) v. Jack Hoogendyk
Carl Levin, the chair of the powerful Armed Services Committee, will easily win reelection over state legislator Jack Hoogendyk. The latest poll gives Levin a big 20% lead.
Minnesota: Al Franken v. Norm Coleman (I)
Norm Coleman could be called an accidental senator; in 2002, Paul Wellstone was polling comfortably ahead of him until Wellstone died in a plane crash and the Democrats had to scramble to find a replacement. Al Franken is back to polling just behind Coleman, as he seems to have gotten over his IRS problems and wasn't impacted much by the Playboy article controversy. Senate Republicans are probably terrified at the prospect of a Senator Franken. Obama should have solid coattails in Minnesota; even if McCain picks Pawlenty to be vice president, he struggles to win Minnesota.
Mississippi: Erik Fleming v. Thad Cochran (I)
Thad Cochran has been in the Senate for a long time and is reasonably popular in Mississippi. Erik Fleming ran against Trent Lott in 2006 and lost by about 30%. He'll do just as well this year.
Mississippi B: Ronnie Musgrove v. Roger Wicker
Trent Lott resigned to become a lobbyist, leaving this seat essentially open. Haley Barbour, Mississippi's governor, appointed Wicker to fill in until the special election in November after Chip Pickering said he didn't want it. This seat is not supposed to be competitive, and yet it is. Ronnie Musgrove, a former governor, is a very conservative Democrat; Wicker has never won a statewide election and has low name recognition outside his former 1st district. Musgrove and Wicker are statistically tied, according to the latest polls.
Montana: Max Baucus (I) v. Bob Kelleher
While Montana trends Republican in presidential politics, it is receptive to prairie populism. Max Baucus is a moderate Democrat and extremely popular, while Bob Kelleher is a Republican, a Republican who calls for increased taxation, socialized medicine, and nationalized oil. Baucus, one of the most powerful Senate members, will cruise to another term.
Nebraska: Scott Kleeb v. Mike Johanns
Chuck Hagel is disgusted with the Bush administration, so he's quitting. Mike Johanns has impressive credentials as a former Nebraska governor and former Secretary of Agriculture. Johanns has consistently polled far ahead of Scott Kleeb, so this seat will probably remain Republican.
New Hampshire: Jeanne Shaheen v. John Sununu (I)
The pair raced to fill an open seat in 2002, and John Sununu won in a far more favorable political environment. However, New Hampshire residents have shown a marked distaste for the Iraq War, as evidenced by Carol Shea-Porter's win in the 1st district, and Sununu supports the war. Jeanne Shaheen has consistently polled ahead of Sununu, so at this point the seat probably leans Democratic.
New Jersey: Frank Lautenberg (I) v. Dick Zimmer
Dick Zimmer's post-primary bounce drew this race into a dead heat a few days ago, but his bounce lasted only one day. A more recent poll shows that Lautenberg leads by 9%, which combined with the New Jersey trend of having Republicans poll well until September/October evidences a fairly safe seat.
New Mexico: Tom Udall v. Steve Pearce
Pete Domenici's retirement led all three members of New Mexico's congressional delegation to vie for the Senate seat. While Steve Pearce, who represents the conservative southern portion, and Heather Wilson, who represents the centrist central portion, squabbled over the Republican nomination, Tom Udall built an impressive lead of 25% over Pearce. While Pearce certainly will recover some since he won the primary, it's still important to put Udall's lead into perspective: he's doing better than two incumbent Democrats from swing states, Carl Levin and Tom Harkin, and they have totally unknown opponents.
North Carolina: Kay Hagan v. Elizabeth Dole (I)
Elizabeth Dole's chairing the NRSC in 2006 was the best thing that could have happened for the Democrats; she got only very weak Republicans to challenge potentially vulnerable Democrats, such as Bill Nelson. Additionally, Obama only polls 2% behind McCain in North Carolina, so his coattails may be enough to help Kay Hagan, a state senator, win.
Oklahoma: Andrew Rice v. James Inhofe (I)
Rising sea levels endanger James Inhofe more than his Democratic opponent; he's more likely to be forced out of Washington by having his house there flooded than by being voted out.
Oregon: Jeff Merkley v. Gordon Smith (I)
This is another top tier race, much like the one in Maine. Gordon Smith is a moderate Republican in a Democratic state, but unlike Susan Collins, he isn't that popular personally. Jeff Merkley, the Speaker of the state House of Representatives, will likely receive coattails from Obama.
Rhode Island: Jack Reed (I) v. TBA
Liberal state + +38% net popularity + strong military credentials = ?
South Carolina: TBA v. Lindsey Graham (I)
Lindsey Graham should take this year to find a wife.
South Dakota: Tim Johnson (I) v. Joel Dykstra
Though initially considered potentially vulnerable thanks to his illness and his razor-thin victory over John Thune in 2002, Tim Johnson is currently polling 35% over his opponent, Joel Dykstra. Johnson is also very popular here, with a net approval rating of an astronomical +46%. Dykstra is put into a very peculiar position: if he doesn't campaign hard, he will lose, but if he campaigns hard against a person who is revered for combatting his illness bravely, he'll come off as mean in this small state where personality usually trumps party affiliation.
Tennessee: TBA v. Lamar Alexander (I)
Lamar Alexander is a former Tennessee governor and has good name recognition. However, his popularity has been slipping as of late, so if the right challenger comes along, he could be vulnerable.
Texas: Rick Noriega v. John Cornyn (I)
John Cornyn is closely associated with George W. Bush, and so his popularity is tied to Bush's. Not even Texas would accept Bush now, so it follows that Texas is not accepting Cornyn. Cornyn leads by double digits over Noriega, but that is probably because Noriega hasn't had time to build up name recognition yet.
Virginia: Mark Warner v. Jim Gilmore
John Warner feels that he's old enough to retire, thereby creating a competitive race. Mark Warner and Jim Gilmore are both former governors of Virginia. However, that's where the similarities stop. Mark Warner is rich, telegenic, and popular. Jim Gilmore is not rich, unattractive (seriously, the most common picture of him has him randomly pointing upwards; according to my mother, that's what I did as a baby when I had diarrhea), and not so popular. Mark Warner has consistently led by double digits through 4 polls, and is likely to get coattails from Obama.
West Virginia: Jay Rockefeller (I) v. Jay Wolfe
Rockefeller is a former governor of West Virginia and has served in the Senate since 1985. Like Arkansas, West Virginia is surprisingly Democratic at the state level. Expect Jay Wolfe to lose badly.
Wyoming: TBA v. Michael Enzi (I)
It's not impossible that the Democrats may beat Michael Enzi. You'll see Santa Claus have a tea party with the Tooth Fairy and the Easter Bunny first, though.
Wyoming B: TBA v. John Barrasso
Craig Thomas died, so John Barrasso was appointed to his seat. However, since Wyoming Governor Dave Freudenthal has refused to run, if you take the Easter Bunny out from the analysis of Wyoming's other seat, you'll have a pretty good idea of what the race here will be like.