WASHINGTON (AP) — President Donald Trump and House leaders revved up pressure Wednesday on balky conservatives and other Republican lawmakers as crunch time approaches on the party’s health care overhaul bill, a drive GOP leaders concede they can’t afford to lose.

A day before the House planned votes on the measure, Trump and top Republicans continued hunting support for what would be a significant achievement for his young presidency. But underscoring the bill’s uncertain fate, a senior administration official said that 20 to 25 House Republicans remained opposed or undecided. That’s a grave figure since united Democratic opposition means the measure crashes if 22 GOP lawmakers vote “no.”

“Big day for health care. Working hard!” Trump tweeted Wednesday.

On Tuesday, Trump told House Republicans at a private meeting at the Capitol that “a loss is not acceptable, folks.” He warned they’d face widespread defeats in next year’s elections and possible loss of control of the chamber if the measure failed. With a smile he told Rep. Mark Meadows, R-N.C., a leading conservative opponent of the measure, “I’m gonna come after you so hard.”

Trump’s remarks and the White House nose count of votes were each described by Republicans who provided inside information on condition of anonymity.

House Speaker Paul Ryan, R-Wis., also painted a gloomy political picture for Republicans if they flop after vowing to demolish former President Barack Obama’s health care law that the GOP has assailed since its enactment in 2010.

“If we don’t keep our promise, it will be very hard to manage this,” the speaker said Tuesday.

The Republican legislation would halt Obama’s tax penalties against people who don’t buy coverage and shrink the federal-state Medicaid program for low earners, which the statute has expanded. It would provide tax credits for medical bills, though generally skimpier than the aid Obama’s statute provides.  It also would allow insurers to charge older Americans more and repeal tax boosts the law imposes on high-income people and health industry companies.

The House Rules committee, usually tightly controlled by GOP leadership, was meeting Wednesday to set the terms of debate.

The panel was expected to let the chamber vote on revisions that top Republicans concocted to win votes. These include adding federal aid for older people and protecting upstate New York counties — but not Democratic-run New York City — from repaying the state billions of dollars for Medicaid costs.

Eager to showcase their support for Obama’s law, House Democrats invited former Vice President Joe Biden to speak Wednesday on the Capitol’s steps. Democrats champion the statute for its expansion of health care coverage to 20 million more people and requiring insurers to cover the very ill, families’ grown children to age 26 and specified services like mental health care.