Progressives are frustrated with 3 features of our government that have been used to block the United States from joining the rest of modern democracies in enacting progressive legislation. One result of the control of our government by undemocratic forces is how poorly we have handled the pandemic by not enacting national methods to address the spread of the virus.
The first progressive reform is possibly the easiest to change and that is the Senate filibuster rule that has been used to require 60 votes to pass the most progressive legislation. Originally designed to provide the minority an opportunity to debate their positions it has become a way for conservatives to block progressive legislation. Of course, it has been used occasionally by progressive but not nearly as often as conservatives. If the Democrats gain the majority in the Senate they may have an opportunity to finally do away with the filibuster.
The second progressive reform is to address ending gerrymandering of legislative districts to block Democrats from being elected. This technique has been used to disenfranchise minority voters in states that have a changing demographic and have the white minority remain in control. Again this has been used by Democrats to control power too as they have in Maryland but it is much more often used by conservative Republicans. Having legislative districts drawn by non-partisan groups makes more sense.
Finally ending the Electoral College is long overdue. Up until the last 20 years, it's undemocratic effect has been an issue as the candidate that won the popular vote also won the Electoral College. We now have seen how twice this institution has caused the loser of the popular vote to win the presidency. Once again this has worked against the more progressive candidate. Being part of the Constitution will make this reform very hard to change in our divided Country. Getting 3/4th of the states to agree on anything today means that we may be prevented to ever change the Constitution again. The success of the "work around" of the Constitution with enough states pledging to award their electoral votes to the winner of the popular votes seems to only be possible when enough red states are turned blue to reach the 270 electoral votes needed to make this work.
I thought of including term limits as another reform but thinking about it this change would probably have a neutral impact on moving progressive legislation.