Progressive outside groups have seized on the 60-vote legislative filibuster as a hurdle for enacting major 2020 ideas including the the Green New Deal climate change resolution and "Medicare for All." They've also called on 2020 candidates to support getting rid of the hurdle and to support other structural reforms.

But Democrats would likely need near unanimous support to nix the filibuster if they can take back the majority. They need three or four seats, depending on which party wins the White House, to gain back control of the chamber. That would likely cap a potential Democratic majority to the low 50s.

So far there aren't the votes within the Senate Democratic Conference for getting rid of the legislative filibuster. In a potential sign of momentum for supporters, Senate Minority Leader(D-N.Y.) said in July that “nothing is off the table.”