WASHINGTON (AP) — Outnumbered and with their party's most powerful leaders arrayed against them, nine moderate Democrats trying to upend plans for enacting President Joe Biden's multitrillion-dollar domestic program face a House showdown.

All the rebellious group must do to prevail is outmaneuver the White House, Speaker Nancy Pelosi and numerous progressive colleagues who've stood firmly against them. That's no small task.

The House meets Monday in what Democratic leaders hope will be just a two-day interruption of lawmakers' August recess. They want quick approval of a budget resolution setting up future passage — maybe this fall — of legislation directing $3.5 trillion at safety net, environment and other programs over the next decade.

That huge measure, largely financed with tax increases on the rich and big business, comprises the heart of Biden's vision for helping families and combating climate change and is progressives' top priority.

The moderates have threatened to oppose the budget resolution unless the House first approves a $1 trillion, 10-year package of road, power grid, broadband and other infrastructure projects that's already passed the Senate. With unanimous Republican opposition expected to the fiscal blueprint, moderates' nine votes would be more than enough to sink it in the narrowly divided House.

The moderates want Congress to quickly send the bipartisan infrastructure measure to Biden so he can sign it before the political winds shift. That would nail down a victory they could tout in their reelection campaigns next year.

"The House can't afford to wait months or do anything to risk passing" the infrastructure bill, Rep. Josh Gottheimer, D-N.J., said Friday. He's a leader of the nine moderate mavericks who each released statements reaffirming their desire that the infrastructure vote come first.

With most of Biden's domestic agenda at stake, it's unimaginable that Pelosi, D-Calif., would let her own party's centrists deal him an embarrassing defeat. That's especially true with the president already under fire over his handling of the U.S. withdrawal from Afghanistan and Democrats' prospects uncertain in the 2022 elections for control of Congress.

Some solution averting a Biden setback in the House seems likely, but it was unclear what that would be.

Pelosi, top House Democrat since 2003, has a long history of doing what it takes to line up the votes she needs on important issues.

She said in a weekend letter to Democratic members of the House that it was critical to pass the budget resolution this week and that any delay threatens the timetable for delivering "the transformative vision that Democrats share."

"It is essential that our Caucus proceeds unified in our determination to deliver once-in-a-century progress for the children," she wrote.

On Friday, her office released a letter from the chair of the Congressional Hispanic Caucus urging lawmakers to support the budget resolution. Four of the nine moderates who've demanded that the infrastructure bill pass first are members of that caucus.

The chair, Rep. Raul Ruiz, D-Calif., wrote that provisions like extended child tax credits and a path to citizenship for many immigrants would provide "an equitable recovery" for Hispanic and other families.

The House Blue Dog Coalition, a group that includes some of the most conservative congressional Democrats, has also said it wants the infrastructure measure passed as fast as possible, but has stopped short of threatening to oppose the budget resolution. Eight of its 19 members are among the nine moderates who have threatened to vote against the budget.

So far, neither the moderates nor the powerful forces confronting them were showing signs of budging.

Biden met virtually with Pelosi and other Democratic leaders and committee chairs late last week. In a show of solidarity, the White House and Pelosi issued similar statements afterward underscoring their determination to approve the measures soon and pointedly ignoring moderates' demand to do infrastructure first.

"The president noted that these policies go to the heart of the values that he ran on," the White House statement said. It said Biden "reiterated his enthusiasm" for signing the $1 trillion infrastructure and $3.5 trillion social and environment bills "as soon as possible."

The House planned a Monday evening vote on a measure opening the door to passage later of the budget resolution, the infrastructure bill and a voting rights measure, another top Democratic goal.

Unless the moderates decide to oppose the procedural measure, Democrats controlling the chamber 220-212 should be able to push it through. To pass any legislation over solid GOP opposition, Democrats can lose no more than three votes.

If the procedural measure passes, leaders planned a vote on the budget resolution Tuesday. Statements from both sides last week showed they remained divided.

Among moderates, Rep. Henry Cuellar, D-Texas, said in an interview, "No progressive is going to cram something down my throat." Rep. Jared Golden, D-Maine, said failure to pass the infrastructure bill quickly "leaves the nation's economy and crumbling infrastructure hostage to political gamesmanship."

On the other side, progressive leader Rep. Katie Porter, D-Calif., said in an interview that Democrats "not actively supporting" Biden's priorities "are not moderates," suggesting they're conservative.

The group Justice Democrats, which recruits progressive candidates including challengers to congressional incumbents, released a fundraising appeal saying Gottheimer was being supported by "the worst of the political establishment." It did not name who they were.