Progressive Democrats in the House and progressive activist groups aren’t just supporting House Minority Leader Nancy Pelosi’s bid to become the next speaker of the House; they’re going so far as to talk about primarying those who oppose her.

Groups like MoveOn, Daily Kos, and Indivisible are keeping a close eye on the list of 16 Democrats who recently released a letter saying they’ll vote against Pelosi.

“If right-wing Democrats end up helping Republicans by voting against Nancy Pelosi as speaker, they can expect to face serious backlash from the same energized and mobilized base of progressive voters that just brought Democrats a majority in the House. Which certainly could extend to primaries,” MoveOn spokesperson Karthik Ganapathy told Vox in a statement.

This underscores the point that the opposition to Pelosi isn’t coming from the left; it’s coming from the party’s centrist wing. The group of so-called “rebels” is largely made up of moderates who are members of the New Democrats and Blue Dogs.

Some progressive members have been signaling their support for Pelosi for months, and the leaders of the Congressional Progressive Caucus recently announced their support for Pelosi after negotiating placement on key committees. Former President Barack Obama showered Pelosi with praise on a recent CNN podcast, calling her “one of the most effective legislative leaders that this country’s ever seen.”

And it’s not just progressive incumbents and party leaders. One of the left’s newest stars, self-proclaimed democratic socialist Alexandria Ocasio-Cortez, has indicated she’s also on board.

Moderate candidates helped propel Democrats to win back the House in 2018. But the dynamics of the current leadership battle show it’s much harder to mobilize moderates — especially when the grassroots activists of the left have emerged as a real force in politics.

Progressives are ideologically aligned with Pelosi — and they’re going to bat for her

Nancy Pelosi is the ultimate negotiator, and the job of speaker means she has to find compromise with moderates and liberal Democrats alike. But the California Democrat has long been ideologically more aligned with the party’s liberal base, so progressives are natural allies for her.

Pelosi was one of the early members of the Congressional Progressive Caucus, which was started in the early 1990s by then-Rep. Bernie Sanders. Pelosi voted against the Iraq War in 2002 and was a champion of marriage equality well before the issue hit the mainstream. Her success passing the Affordable Care Act in 2010 has won her legions of supporters on the party’s left wing, especially as President Donald Trump and the Republicans have tried to repeal the health care law.

When climate activists showed up in her office with Ocasio-Cortez on the first day of new member orientation to demand the new Congress take action on climate change, Pelosi welcomed them with open arms. She tweeted her support for the protest and encouraged the creation of a new subcommittee to examine and address climate issues.

Progressives know that Pelosi shares their interests and is an important ally to make, and new members seem to recognize that as well. Ocasio-Cortez recently indicated she would be supporting Pelosi in the speaker’s race. Pelosi has no formal challenger yet, but past challengers, including Rep. Tim Ryan (D-OH), are decidedly more moderate. Ocasio-Cortez spoke to the progressive fear that whoever challenges Pelosi won’t actually have the interest of the left in mind.

“Right now, out of the field, I would say that [Pelosi] is the most progressive candidate,” Ocasio-Cortez told her Instagram followers during a recent post. “All of the rebellion for the Speakership are challenges to her right … My standard in this is: I’m going to support the most progressive candidate that’s leading the party, and right now, that is Nancy Pelosi, in terms of the running. I would like to see new, younger leadership, but I don’t want new leadership that’s more conservative.”

With the support of progressive groups locked up, Pelosi has a powerful grassroots army at her hands. They may not be able to successfully primary some of the incumbents who oppose Pelosi, but nevertheless, it’s a warning shot: Cross her, and life could become much more difficult for you.

Current progressive leaders want to be more powerful. Allying with Pelosi is a way to do that.

After keeping quiet for weeks, progressives announced late last week that they had cut a deal with Pelosi, agreeing to put more progressive members on key committees including Ways and Means, Energy and Commerce, Appropriations, Financial Services, and Intelligence.

“Specifically, we are pleased that Leader Pelosi shares our commitment to ensuring that CPC members are represented proportionally on the key exclusive committees,” Reps. Mark Pocan (D-WI) and Pramila Jayapal (D-WA), the leaders of the Progressive Caucus, said in a statement.

This underscores an important point: Progressive members within Congress are working very much within the existing system that Pelosi runs effectively. Pelosi is shoring up her support for the speaker’s race with commitments like these: committee assignments, creation of subcommittees, and of course, promises of money for 2020 races.

Progressives are playing the long game. By getting more members on powerful committees, they are building an influential base of support within Congress and laying the framework for more progressive candidates to ascend into leadership in future years.

They understand their interests are better served backing Pelosi, and some have been hesitant to push too far on progressive policy issues.

Rep. Ro Khanna (D-CA) recently laid out to Vox a laundry list of items progressives want to see Pelosi put up for a vote: a $15 minimum wage, Medicare-for-all, and a green New Deal. He even suggested members of the Progressive Caucus should withhold their votes until Pelosi committed to addressing them. But Khanna didn’t go so far as saying he’d withhold his own vote for Pelosi to get a promise for votes on progressive bills. After all, he added, they’re longtime friends.

With Trump in the White House and Republican Mitch McConnell controlling the Senate, progressives in the House know they have very little sway in making real policy. They know that to pass big, bold ideas like Medicare-for-all, they need to get power in the Senate and the White House first.

For now, they realize that staying united behind Pelosi might be the easiest path to getting things done.