This is a 3 step plan where I think Democrats should go if they win 2020.. (If I were elected with razor thin, 50+ VP tiebreaking Senate Majority)
1) Climate Change - immediately rejoin the Paris Accords, re-instate all of Obama-era executive orders / roll-back all of Trump's anti-environment regulation rollbacks.
2) Entrench Democratic Power - this is what Republicans get right and Democrats are clueless. The first major pieces of legislation need to be restoring democracy (which means entrenching the power of the majority of voters which are Democrats).
First, End the Fillibuster - all future legislation will require doing this
Second, Pass H.R.1. - The 116th Congress, headed by the House Democrats passed sweeping legislation restoring voting rights, making election day a federal holiday, and widely expanded voter registration. This basically nullifies Republican voter suppression.
Third, Grant Statehood to DC and Puerto Rico - this likely gives 4 more Democratic Senators
3) Pass Smaller, Meaningful, Kitchen Table Legislation
First, you raise the minimum wage to $15 / hour with an immediate bump to $9 / hour, phased in additional $1 per hour reaching $15 / hour by 2026, indexed to inflation each year after.
Second, you pass equal pay for women and expanded family leave benefits
Third, you restructure the Trump tax law to raise taxes on the wealthy, tax wall-street speculation, cut taxes on the middle class, and lift the cap on FICA (while expanding Social Security Benefits)
Fourth, pass a sweeping funding package for infrastructure capital improvements
Fifth, make right-to-work laws illegal.
Health Care, anti-corruption, and a sweeping New-Deal esque climate package should wait until your second term. Don't touch any of them with a 10 foot pole.