WASHINGTON — President Joe Biden and Democrats agreed to tighten eligibility limits for stimulus checks Wednesday, bowing to party moderates as leaders prepared to move their $1.9 trillion COVID-19 relief bill through the Senate.

At the same time, the White House and top Democrats stood by progressives and agreed that the Senate package would retain the $400 weekly emergency unemployment benefits included in the House-passed pandemic legislation. Moderates have wanted to trim those payments to $300.

Democrats have no choice but to broker compromises among themselves, thanks to their mere 10-vote House margin and a Senate they control only with Vice President Kamala Harris’ tie-breaking vote. The party’s moderate and progressive factions are competing to use their leverage, but without going so far as to scuttle an effort they all support.

So far, Republicans have presented a unified front. But Sen. Lisa Murkowski, R-Alaska, didn’t rule out breaking ranks and supporting the measure. She told reporters her state’s tourism industry has been walloped by the pandemic and said she’s talked to administration officials about “how this helps a state like Alaska.”

Democrats were hoping to begin Senate debate later Wednesday, but they faced mountains of GOP amendments and other delays that could take days to plow through. The House will have to approve the Senate’s version before shipping it to Biden, which Democrats want to do before the last round of emergency jobless benefits run dry March 14.

“I would expect a very long night into the next day and keep going on,” said Sen. James Lankford, R-Okla., describing GOP plans to force votes.

Under the legislation, individuals earning up to $75,000, and couples up to $150,000, would get $1,400 checks per person. The House-approved version would gradually phase down that amount, with individuals making $100,000 and couples earning $200,000 receiving nothing.

Under Wednesday’s agreement, the Senate bill would instead halt the payments completely for individuals making $80,000 and couples earning $160,000, said a Democratic official, who described the agreement only on condition of anonymity.

That means some people who received the last round of $600 relief checks approved in December wouldn’t get anything this time. The liberal Institute on Taxation and Economic Policy estimated that the pared-down Senate eligibility levels means 280 million adults and children would receive stimulus checks, compared to 297 million people under the House plan.

West Virginia Sen. Joe Manchin, perhaps the chamber’s most conservative Democrat, has favored lowering the relief check eligibility limits. He suggested Wednesday he’d back the emerging Senate legislation, saying it “really does have enough good stuff that we should be able to make this work.”

Liberals were already angry after Senate Democrats jettisoned the House bill’s minimum wage increase to $15 by 2025.

They did so after the Senate parliamentarian said the chamber’s rules wouldn’t allow the boost in this bill.