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The Five Blocs In Congress To Watch In Biden’s Washington 

President Biden started off his tenure with a bunch of executive orders and directives. But to get most really big things done, he will need to go through Congress. So it’s worth looking at the new Congress and where Biden might find support and opposition to his policy goals.

Let’s start with the big picture. The U.S. House has 222 Democrats and 211 Republicans.1 So Democrats in the House can afford to lose no more than five members’ votes and pass any legislation that doesn’t have GOP support.

In the Senate, Democrats have control but only barely, with Vice President Kamala Harris able to cast a tie-breaking 51st vote in a chamber where each party has 50 senators. Democrats can’t afford any defections on party-line votes. And generally, only judicial and Cabinet nominations and some budget bills can be passed with a simple majority in the Senate. So unless Democrats move to get rid of the filibuster, they would need the support of at least 10 Republicans in the Senate to pass bills.2

Look closer, though, and there’s a lot more going on in the new Congress. Here are the factions and members on Capitol Hill to watch over the next two years:

The median Democrats

In this partisan era, getting universal support from Democrats in the House and Senate is probably the most important step in any effort by the Biden administration to pass legislation. So it’s worth first looking at the median Democratic members in Congress.

In the Senate, the ideological center among the 47 Democrats and Democratic-leaning independents in the 2019-20 Congress was Illinois’ Richard Durbin (the 23rd most liberal Democrat according to DW-Nominate scores, which measure legislator’s ideology by their roll-call votes), Michigan’s Debbie Stabenow (24th most liberal) and Illinois’ Tammy Duckworth (25th). By FiveThirtyEight’s Trump score, which looked at how often members voted in line with Trump’s position, the Democratic senators in the middle of the party were Oregon’s Ron Wyden, Delaware’s Chris Coons and Vermont’s Patrick Leahy. In the House, this median group includes Susan Wild of Pennsylvania, Darren Soto of Florida, and John Yarmuth of Kentucky, per DW-Nominate.

You probably don’t know much about these members and that’s exactly the point — they are, at least ideologically speaking, kind of generic, unremarkable Democrats. If Biden proposes something and a few of these nine strongly oppose it, the new president should be very nervous.

The most conservative Democrats

This is the second-most important group, in my view. It’s likely the most liberal Democrats in Congress will object to some of Biden’s agenda just as intensely as their conservative counterparts, if for different reasons. But more conservative Democrats are likely to suggest they fundamentally disagree ideologically with some of Biden’s proposals and that those proposals will hurt them electorally and be willing to vote them down.

Who are the more conservative Democrats? Arizona’s Kyrsten Sinema and West Virginia’s Joe Manchin are on the right-most edge of the party in the Senate, according to both DW-Nominate and Trump Score. And I would expect Arizona’s Mark Kelly to join that group, both because he ran as a fairly moderate candidate and because he must run for reelection next year in a state that is very evenly divided between the two parties. In the House, more conservative members include Virginia’s Elaine Luria, Pennsylvania’s Conor Lamb, Oregon’s Kurt Schrader and Florida’s Stephanie Murphy. Murphy and Schrader are part of the 18-member Blue Dog Coalition, which includes the most conservative Democrats and is likely to act as a bloc and fight legislation they feel is too liberal.

The most liberal Democrats

The most liberal Democrats are probably less likely to vote against Biden proposals compared to their conservative counterparts for two reasons. First, they will have no credible claim that voting for something that Biden favors would hurt them electorally, since more liberal members predominantly represent safely Democratic districts and states. Secondly, it’s hard for a member of Congress to tank a bill that he or she mostly agrees with but thinks doesn’t go far enough.

That said, progressives in the House did block some of House Speaker Nancy Pelosi’s proposals in 2019 and 2020 and are likely to act as a check against Biden going too far to the right in the view of the party’s progressives.

I would expect Sens. Bernie Sanders and Elizabeth Warren (the most liberal senator according to DW-Nominate) to be the most prominent voices in the Senate trying to push legislation to the left. In the House, expect to see new members Jamaal Bowman of New York and Cori Bush of Missouri essentially become new members of “The Squad” (Alexandria Ocasio-Cortez of New York, Ilhan Omar of Minnesota, Ayanna Pressley of Massachusetts and Rashida Tlaib of Michigan) and that bloc to be the left flank in the House. Another very liberal House member to watch is Pramila Jayapal of Washington, the leader of the Congressional Progressive Caucus, which includes about 100 members.

The most liberal Senate Republicans

It will not shock you that Maine’s Susan Collins and Alaska’s Lisa Murkowski are the most liberal Senate Republicans by basically every measure. Biden and Collins have both talked about their strong and long-standing relationship. So if Collins is balking at something Biden proposes, he should probably assume that no other Republican will vote for it either. (I emphasized Republican senators here, because Biden doesn’t really ever need votes from House Republicans, since the minority party cannot filibuster legislation in the lower chamber.3

The other potential swing votes among Senate Republicans

The ideological scores don’t give us a very clear sense of the more liberal Republicans after Collins and Murkowski. Sens. Mitt Romney of Utah and Ben Sasse of Nebraska were both critical of how former President Trump broke with democratic norms and values, but they are fairly conservative on policy and I would not expect them to embrace some of the big spending plans that Biden has proposed.

Still, if I were pressed to come up with 10 or so Republicans who might join some piece of legislation that Biden backed but many other Republicans opposed, I would add Romney and Sasse to Collins and Murkowski. That gives us four. After that as possibilities? I’d go with Sens. Richard Burr of North Carolina, Rob Portman of Ohio and Pat Toomey of Pennsylvania (all aren’t running for reelection in 2022); Sens. Lindsey Graham of South Carolina and Chuck Grassley of Iowa (both can be somewhat ideologically idiosyncratic at times), and Sens. Bill Cassidy of Louisiana, Shelley Moore Capito of West Virginia, Jerry Moran of Kansas and Todd Young of Indiana, all of whom have been involved in bipartisan negotiations on COVID-19 relief bills over the last few months.

All of those GOP senators except for Collins and Murkowski are quite conservative. So some big Biden proposal that peels off just enough Republican votes to get through a filibuster and pass in the Senate is unlikely. Instead, anything that Biden proposes that wins over those 10 or so Republicans is likely to be so inoffensive to conservatives that it passes 80-20, with most Republicans on board, instead of passing 60-40 with only this bloc of GOP senators embracing it.

This breakdown gives you a sense of the big challenges for Biden. In both the House and the Senate, there are enough very progressive Democrats to kill legislation, and at the opposite ideological end, there are also enough more conservative Democrats to kill legislation. The Senate has only two true centrist Republicans (Collins and Murkowski), so if something requires 60 votes, Biden somehow has to convince at least eight conservatives to go along with him.

Where does that leave the Biden administration? We’ll have to wait and see, but a few things are more likely to happen than not over the next two years, in my view.

1. The Senate is likely to approve Biden’s judicial and executive branch nominations — and a lot of Republicans may back those picks because the GOP votes don’t mean much since Democrats can get these nominations through by a simple majority anyway.

2. In the House, a lot of Democratic bills will pass, even as The Squad criticizes the bills as insufficiently liberal and the moderates suggest they are too liberal.

The big question will be what happens to bills that pass the House but don’t have 60 votes in the Senate. That dynamic is is likely to lead to …

3. A lot of liberal angst over the filibuster. We’re already seeing calls from progressive activists to get rid of it, but Manchin and Sinema in particular seem very inclined to keep the filibuster in place. Expect this intra-party debate to continue.


  1. There are currently two vacancies. Republican Luke Letlow, who was elected in Louisiana’s Fifth District, died in December. A winner has not been determined in New York’s 22nd District, where incumbent Democrat Anthony Brindisi ran against Republican Claudia Tenney.

  2. In a few instances, there are votes that require a supermajority of 67, such as impeachment or overriding a presidential veto.

  3. OK, but just to be completist, who are the most liberal House Republicans? If the Biden administration wants to get some votes from moderate Republicans for optical reasons, let’s say, the obvious targets are the members who aren’t as conservative as their GOP colleagues according to their voting records, such as New York’s John Katko, Pennsylvania’s Brian Fitzpatrick, New Jersey’s Chris Smith and Michigan’s Fred Upton. Another GOP lawmaker whom Biden’s team is likely to court is Rep. Tom Reed of New York, the co-chair of a bipartisan group called the Problem Solvers Caucus.

Perry Bacon Jr. was a senior writer for FiveThirtyEight.