President Biden’s legislative ambitions face a crucial test in the narrowly divided Congress this month, with key Democratic senators signaling they want to pump the brakes as party leaders move to quickly pivot from last month’s $1.9 trillion pandemic relief act to an even larger infrastructure and jobs bill and other pressing policy items.

Republican leaders, meanwhile, are beginning to mount fierce opposition to those plans, even as a subset of GOP centrists share rising frustration about a lack of meaningful outreach from Biden, who has billed himself as a bipartisan dealmaker.

With lawmakers returning Monday from a two-week Easter recess, those crosscurrents could turn the coming weeks into a make-or-break moment for some of Biden’s biggest initiatives — and perhaps a final chance to demonstrate whether bipartisan cooperation will be possible.

President Biden said on April 7 that he is open to compromising with Republicans on his proposed $2 trillion infrastructure plan. (The Washington Post)

On one hand, liberal Democrats are pressing Biden to take advantage of high approval ratings and a popular legislative agenda to sweep GOP opposition aside and move swiftly on trillions of dollars of new spending and potential tax hikes on corporations and wealthy Americans, as well as legislation to restrict guns, expand voting access and secure civil rights for LGBT Americans.

“The time is now to go forward,” said Senate Budget Committee Chairman Bernie Sanders (I-Vt.), who said he is already preparing to use special procedures to allow Democrats to pass legislation without Republican support. “This country faces enormous crises that have got to be addressed right now. When you have half a million people who are homeless, I’m not going to slow down. . . . When the scientists tell us we have five or six years before there will be irreparable damage done because of climate change, I’m not going to slow down.”

On the other hand, some Democrats are pressing Biden and Senate Majority Leader Charles E. Schumer (D-N.Y.) to negotiate with Republicans. Most conspicuously, moderate Sen. Joe Manchin III (D-W.Va.) vowed Wednesday in a Washington Post op-ed to never “eliminate or weaken” the filibuster while also casting doubt on using the special budget procedures Sanders is exploring to fast-track bills.

Sen. Joe Manchin (D-W.Va.) explained on March 7 why he stalled the coronavirus relief vote, a day after the Senate approved the package without Republicans. (The Washington Post)

“The time has come to end these political games, and to usher a new era of bipartisanship where we find common ground on the major policy debates facing our nation,” he wrote, adding: “Generations of senators who came before us put their heads down and their pride aside to solve the complex issues facing our country. We must do the same.”

In a Wall Street Journal interview published a day earlier, Sen. Kyrsten Sinema (D-Ariz.) also defended the current rules and called on senators “to change their behavior and begin to work together, which is what the country wants us to do.”

The statements from both Manchin and Sinema were consistent with their past positions, which have defended the role of the filibuster — the long-standing Senate rule that has evolved into a de facto 60-vote supermajority requirement for most legislation — and promoted the need for cross-aisle cooperation.

But the timing of Sinema’s interview and Manchin’s op-ed — and his warnings about using the special budget “reconciliation” rules for another massive spending package — have galvanized attention on Capitol Hill and at the White House, with key officials mindful that every lawmaker’s opinion matters in a 50-50 Senate.

While there is some private frustration among Senate Democrats with Manchin, senators acknowledge that as a Democratic elected official from a deeply conservative state, Manchin should be afforded more leeway than others in the caucus in departing from the party line. But several senators and aides said the appetite for bipartisan talks is limited, with some suggesting that Manchin and others had until the end of the month to demonstrate that Republicans would engage in meaningful negotiations.

“I just think that Joe Manchin wants good things for the country and for the people of West Virginia, and if Republicans stand in the way, maybe he’ll rethink some of the views that he expressed in that op-ed,” Sen. Richard Blumenthal (D-Conn.) said.

White House officials do not plan to change their strategy toward the Senate, despite mounting signals that Biden’s agenda will run into potentially insurmountable procedural hurdles maintained by his own party. The president himself has remained unclear on his filibuster position, criticizing the tool as a relic of the Jim Crow era yet not saying he would support being able to pass all bills with a simple majority of votes in the Senate.

While large portions of Biden’s jobs plans could pass using reconciliation, other bills that don’t directly involve government spending — including a proposed national overhaul of voting and campaign finance law that is a top party priority — cannot pass with a mere 51 votes due to Republican opposition.

At the White House, officials have repeatedly deferred to lawmakers and said they see all of the maneuvering by Manchin and others as part of a long process that will play out over the course of weeks and months.

“The president believes that there’s a path forward to get this American Jobs Plan passed with bipartisan support,” White House press secretary Jen Psaki said Thursday when asked about Manchin’s op-ed. “That’s why he’s going to invite Democrats and Republicans here. That’s why he’s going to hear from them on their ideas that they’ve already put forward.”

Biden plans to meet Monday with a bipartisan group of lawmakers to discuss the administration’s jobs plan, Psaki said Friday.

But Biden is facing growing skepticism that he will be able to cut any kind of deal with Republicans. Senior GOP leaders have come out strongly against the scope and nature of the president’s emerging infrastructure and jobs plan, which already includes more than $2 trillion in spending, with proposals costing trillions of additional dollars expected to be rolled out later this month.

Senate Minority Leader Mitch McConnell (R-Ky.) ruled out any bipartisan support for Biden’s central funding mechanism — an increase in the corporate income tax rate from 21 to 28 percent, partially rolling back a 2017 Republican tax cut — saying his party would fight the move “every step of the way.” Conservative lawmakers and advocacy groups have also taken aim at the broad variety of spending in the plan, accusing Biden and Democrats of misleading Americans by billing his proposal as infrastructure.

Meanwhile, the small group of GOP senators who have shown a willingness to negotiate with Democrats — including moderates Susan M. Collins (Maine), Lisa Murkowski (Alaska) and Mitt Romney (Utah) — have given signals of rising frustration.

When Biden said Wednesday that Republicans “didn’t move an inch” from their initial offer, the 10 GOP senators involved released a blistering statement accusing Biden and Senate Democrats of not seriously pursuing a compromise, accusing them of “roundly dismiss[ing] our effort as wholly inadequate in order to justify its go-it-alone strategy.”

A senior aide to a moderate Republican senator said the group was wary of entering another negotiation, only for it to be “another sort of Kabuki dance just to show Biden tried.”

“What on earth would lead them to believe it would be any different this time than it was last time?” said the aide, who was not authorized to speak publicly and spoke on the condition of anonymity to candidly describe the group’s internal thinking.

But there is little appetite among liberal Democrats and their allies for extended negotiations with Republicans — with veteran lawmakers among them eager to avoid a repeat of 2009, when Democrats spent months negotiating with GOP senators such as Charles E. Grassley (Iowa) and Olympia J. Snowe (Maine) as they fruitlessly tried to get them on board with then-President Barack Obama’s health-care overhaul.

Now, Democratic lawmakers and advocacy groups are pressuring their colleagues to act swiftly, lest they squander both time and political capital. Adding to the pressure for action is the desire among many Democrats to pass voting rights legislation ahead of the 2022 midterms, with sufficient time to allow state elections officials to implement the changes.

“The clock is ticking,” said former Democratic Senate aide Eli Zupnick, spokesman for Fix Our Senate, a coalition of liberal groups pushing for elimination of the filibuster. “The choice is to have this take a long time and not get things done, or to move quickly, force these decisions to be made, to force Republicans to show their cards.”

To help build pressure, Fix Our Senate is launching a two-week ad buy next week targeting at least four states with senators who have yet to endorse rules changes. “Tell your senators to protect our democracy, not the Jim Crow filibuster,” a narrator says.

For Senate Democratic leaders, Manchin’s latest statement did little to change their thinking on handling internal doubts about changing the filibuster. Schumer has repeatedly said that Democrats would make a joint decision as a caucus on how to move forward once Republicans block crucial piece legislation. But he has yet to tee up any key bills for floor votes, with gun control, voting rights and civil rights bills all short of 50 votes as it stands.

Manchin earlier this year appeared to endorse a possible change to Senate rules that would mandate a “talking filibuster,” which would make a legislative blockade a much more physically and politically taxing experience. Manchin did not mention that proposal in his op-ed, and Sen. Jeff Merkley (D-Ore.), its lead proponent, said he believed Manchin could ultimately support it as a “strengthening,” not a weakening, of the filibuster.

“I think ultimately we’re going to have 50 Democratic senators who say: How do we honor our oath to the Constitution?” Merkley said. “How do we make sure that the process on the floor of the Senate isn’t one that encourages tribal, partisan obstruction but instead encourages the development of good, solid legislation? And out of those conversations, I think we can find a path forward.”

The other alternative is reconciliation, and Sanders said Friday that he expects the vast Biden package — which could ultimately include not only infrastructure but health care and other provisions — to move under those rules.

Schumer last week touted a new parliamentarian ruling that could allow Democrats to break the spending bill up into discrete chunks and still pass them all under the fast-track procedures. But details of the ruling have yet to be worked out, and no Democrat seems quite sure if passing two smaller bills would be any easier than passing one big one.

“The answer is, nobody knows,” Sanders said. “But it is definitely a step forward in giving us more flexibility.”

Sanders would not discuss a timeline to prepare the next reconciliation vehicle, which, he said, depends on talks with Schumer and the White House. “But,” he added, “we will be ready to go in a short period of time.”

Asked how much time should be spent talking with Republicans, Sanders was blunt: “If they’re not serious, it should be no time. If they are serious, you know, we have some time. . . . We will have a sense very shortly whether Republicans are serious.”

There are forces lining up, however, to try to force a more bipartisan process — and they are counting on senators like Manchin and a handful of moderates in the closely divided House to help make that happen.

The U.S. Chamber of Commerce, for instance, has already staked out a position that is supportive of Biden’s infrastructure ambitions but sharply critical of his plans to pay for them.

Neil Bradley, the Chamber’s executive vice president and chief policy officer, said Friday that the business group has been“encouraging quiet private negotiations, considerations, and explorations of other ideas and ways of approaching this.”

“There’s no question that how the American Rescue Plan came together has made a lot of people gun-shy about the prospect of a future bipartisan negotiations,” he said, adding that Democrats felt they had to act quickly on the rescue bill: “There is time here for negotiations.”

But Seth Hanlon, a senior fellow at the liberal Center for American Progress who served as an economic policy adviser to President Barack Obama, said that at some point the pressure on Democrats to deliver results ahead of the 2022 midterms will overwhelm the internal disputes. He pointed to the 2017 Republican tax bill, which passed on party-line votes after a previous attempt to repeal and replace the Affordable Care Act failed following months of effort.

“Time is precious, especially in the Senate, and more time that is spent not getting your major priorities in motion is just time wasted,” he said. “At some point, it’s going to be abundantly clear that the choice is not between bipartisanship and budget reconciliation — it’s between budget reconciliation and nothing at all.”