WASHINGTON — For Rep. Brendan Boyle, it’s a moment for Democrats to go big.

With a bipartisan infrastructure bill set for a House vote Monday, the Philadelphian says he wants it approved — but only if House and Senate Democrats also advance a separate, sweeping $3.5 trillion package of social safety net programs.

“This is the first opportunity in over a half century to do big, bold things that will transform our country,” he said at an event last week in Philadelphia. “One way or the other, we must pass both bills.”

Rep. Susan Wild, of Allentown, also wants both to advance, but she’s ready to pass the $1 trillion infrastructure plan now, and is hoping for trims to the bigger one.

“I’m a firm ‘yes’ on the ‘hard infrastructure’ bill whenever they bring it up, and I hope we get it done ASAP,” she said in a telephone interview. She said she supports the “human infrastructure” package on social spending but that it’s “probably a good idea” if the cost comes down. “I don’t think we’re going to see a $3.5 trillion bill under any circumstances.”

The diverging views reflect the competing approaches now splitting the party ― across the region, state, and country — and threatening two central elements of President Joe Biden’s agenda.

At stake are some of Democrats’ biggest policy goals, and much of the political capital they hope to build for next year’s midterm elections. Some, like Wild, are hoping to campaign on the tangible benefits they say these bills would provide. But failure could raise serious questions about their ability to govern, even with full control of Congress and the White House. It would also deal another blow to a president whose approval rating has plummeted amid criticism over his Afghanistan withdrawal, rising coronavirus cases, and influx of migrants.

“It’s a huge concern of mine,” said Wild, who represents one of Pennsylvania’s most competitive House districts. “If you don’t get at least one of these bills done — specifically the hard infrastructure and preferably both — we are at substantial risk next year.”

Monday’s vote, demanded by Democratic moderates, would give final approval to the $1 trillion package that would fund upgrades for roads, bridges, public transit, and broadband internet. It already passed the Senate with bipartisan support. But all signs indicate that House progressives have the votes to block it as they urge the party to pass both measures — together.

House Speaker Nancy Pelosi aimed to ease the tensions Friday by announcing steps to also advance the larger package. But with the bill still in flux and the two factions still at odds over its size, that seemed unlikely to break the impasse. Biden also acknowledged a “stalemate at the moment” but was hopeful for a resolution.

Neither Democratic faction can act without the other, since the party has such narrow control over the House and Senate. But each wants the other to put their cards on the table first.

» READ MORE: Democrats are counting on Biden’s big economic agenda, while Republicans point to inflation

Moderates like Wild worry that holding out for the big bill could stifle a popular plan that’s on the verge of becoming law. Some worry the cost might be more than taxpayers are willing to swallow.

Progressives say they are pressing to pass the full scope of Biden’s agenda, not just a piece of it. If the smaller bill passes they fear moderates might walk away, leaving the bigger plans to wither. Rep. Dwight Evans (D., Pa.) said House members should send “the strongest possible” bill to the Senate “rather than negotiate against ourselves.”

“We need both bills to keep the promise to Build Back Better after the pandemic,” Evans said in a statement referring to the larger, Democrat-only plan.

Similarly, Rep. Mary Gay Scanlon (D., Pa.) urged her party to “assert pressure on the Senate” by passing a package “that provides life-changing benefits for every American.”

“There are limited opportunities to leverage in order to ensure I’m able to deliver the most good for my constituents, and tying these bills together is one of them,” Scanlon, of Delaware County, said in a statement.

The debate over how to proceed is perhaps the most concrete test of a long-running argument within the party over its approach to policy and politics: Should it take an incremental approach that can appeal to moderate voters? Or pursue aggressive action to meet what progressives say are the deep challenges of the moment? Those competing Democratic visions are already playing out in the U.S. Senate primary race in Pennsylvania.

And they reflect the different elements of the party’s coalition.

Boyle and Evans represent a city where progressives have increasing sway and where the biggest political challenge is likely to come from the left rather than from Republicans. Wild is from a competitive Lehigh Valley district that Democrats only regained in 2018, and where swing voters are critical.

She and others in similar situations are wary of voting on ambitious legislation that might not pass, especially with some Senate moderates balking at the price tag.

“It’s not terribly useful to pass legislation either just in the House or in the Senate if it’s not going to go to the president’s desk,” said Rep. Chrissy Houlahan (D., Pa.).

The “hard infrastructure” bill, which cleared the Senate with bipartisan support, would help rebuild the country’s outdated infrastructure and expand internet access.

The $3.5 trillion measure, which Democrats hope to pass unilaterally, is expected to provide child care subsidies and tuition for two years of community college; extend the child tax credits Democrats passed earlier this year; and fund universal preschool, Medicare expansion to cover dental, hearing, and vision, and paid family and medical leave. There could be hundreds of billions of dollars for clean energy and other environmental priorities.

It would raise income taxes on households earning more than $450,000 a year, impose a 3% surtax on those making more than $5 million, and raise the corporate tax rate to 26.5% for companies with income over $5 million.

Republicans universally oppose the larger bill, calling it a liberal wish list that would spend too much, raise taxes too far, and spike inflation. The smaller so-called hard infrastructure measure won 19 GOP votes in the Senate, though a majority still opposed it. “Too expensive, too expansive, too unpaid for,” Sen. Pat Toomey (R., Pa.) said when he voted against it in August.

But with that piece already through the Senate, and Democrats pushing the second measure through a Senate procedure that sidesteps the usual 60-vote requirement, they could approve both measures on their own — if they can work out their internal disputes.

Chester County’s Houlahan, like Wild, supports the social spending plan but also raised concerns about the price tag. She argued that Democrats should pass what they can now.

“Much of our infrastructure is really hurting,” said Houlahan, whose district is also potentially competitive in next year’s election.

» READ MORE: Here’s what Pa.’s and N.J.’s chunk of the $1 trillion infrastructure bill might buy

The tension is high enough that some lawmakers are avoiding public stands. Rep. Andy Kim (D., N.J.), who represents a battleground district, declined to comment through a spokesperson.

Rep. Donald Norcross (D., N.J.) is committed to passing Biden’s entire economic agenda, a spokesperson said.

Rep. Madeleine Dean (D., Pa.), through a spokesperson, expressed faith that the party would get both measures over the finish line.

Rep. Conor Lamb (D., Pa.), who is running in a competitive U.S. Senate primary and helped negotiate some of the framework of the infrastructure bill, will vote for the bipartisan measure “as soon as possible,” he said in a statement. He added that he supports the second piece, though he was less firm about its size, saying he’ll vote for what comes out of House and Senate negotiations.

Among Republicans, meanwhile, Rep. Brian Fitzpatrick of Bucks County is waging a sometimes lonely fight to secure GOP votes for the “hard infrastructure” bill.

As cochair of the bipartisan Problem Solvers caucus, Fitzpatrick expects eight to 10 Republicans to support the measure, though that was before GOP leaders began pushing their members to oppose it.

A bill that has support from both the business and labor groups and that won 69 Senate votes should be “a no-brainer,” Fitzpatrick said. But he said linking the two bills could repel the GOP votes that might help the compromise package overcome Democratic defections.

“Our country’s starving for a bipartisan win right now,” he said. “We have one right in front of us.”