By Richard Cowan and Dustin Volz

WASHINGTON (Reuters) – Republicans in Congress said they lacked the votes needed for passage of their U.S. healthcare system overhaul and a key committee chairman came out in opposition after Donald Trump demanded a vote on Friday in a gamble that could hobble his presidency.

Amid a chaotic scramble for votes, House of Representatives Speaker Paul Ryan, who has championed the bill, met with Trump at the White House. Ryan told the president there were not enough votes to pass the plan, U.S. media reported.

The showdown on the House floor follows Trump’s decision to cut off negotiations to shore up support inside his own party, with moderates and the most conservative lawmakers balking. On Thursday night he had issued an ultimatum that lawmakers pass the legislation that has his backing or keep in place the Obamacare law that Republicans have sought to dismantle since it was enacted seven years ago.

“We’ll see what happens,” Trump said at the White House, adding that Ryan should keep his job regardless of the outcome.

The White House said the vote was set for about 3:30 p.m. (1930 GMT) on Friday on the bill to replace Democratic former President Barack Obama’s signature domestic policy achievement, the 2010 Affordable Care Act, widely known as Obamacare.

“There’s nobody that objectively can look at this effort and say the president didn’t do every single thing he possibly could with this team to get every vote possible,” White House spokesman Sean Spicer told reporters.

Republicans control Congress and the White House but have deep divisions over the first major legislative test since Trump became president on Jan. 20.

In a blow to the bill’s prospects, House Appropriations Committee Chairman Rodney Frelinghuysen announced his opposition, expressing concern about reductions in coverage under the Medicaid insurance program for the poor and the retraction of “essential” health benefits that insurers must cover.

“We need to get this right for all Americans,” Frelinghuysen said.

Representative Rodney Davis, a member of the House Republican team trying to win passage, said the bill was short of the needed votes, and White House budget director Mick Mulvaney added it was unclear if enough support was present.

Vice President Mike Pence, a former House member and influential among Republican lawmakers, postponed a planned trip to Arkansas and Tennessee to help secure passage.

“I’m still optimistic,” Spicer said. “I feel like we’re continuing to work hard. But at the end of the day you can’t force somebody to do something.”

Trump and House Republican leaders cannot afford to lose many votes in their own party because Democrats are unified in opposition, saying the bill would take away medical insurance from millions of Americans and leave the more-than-$3 trillion U.S. healthcare system in disarray.

Republican supporters said the plan would achieve their goal of rolling back the government’s “nanny state” role in healthcare.

FOREHEAD TATTOO

House Democratic leader Nancy Pelosi said, “What’s happening today is a lose-lose situation for the Republicans. It’s a lose-lose for the American people, that’s for sure. But the people who vote for this will have this vote tattooed to their foreheads as they go forward.”

Failure of the measure would call into question Trump’s ability to get other key parts of his agenda, including tax cuts and a boost in infrastructure spending, through a Congress controlled by his own party.

“If it doesn’t pass, this issue is dead,” Republican Representative Mario Diaz-Balart, a bill supporter, said of Republican healthcare legislation. “This is the one shot.”

Even if the legislation passes in the House, it faces an uncertain future in the Senate, where Republicans have expressed misgivings.

Healthcare was the first major test of how Trump, a real estate magnate who touted his deal-making prowess in the 2016 presidential campaign, would work with Congress. Days of negotiations led to some changes in the bill but failed to produce a consensus deal.

U.S. stocks were mixed on Friday in early afternoon trading, having pared earlier gains, while U.S. treasuries were mostly higher.

Leading Republicans had taken to the House floor to make their case to pass the bill and implored conservatives to seize the opportunity to make good on the party’s long promise to get rid of Obamacare.

‘ONLY OUR FIRST STEP’

“Today we are faced with a stark choice,” said Republican Diane Black, who heads the Budget Committee. “While no legislation is perfect, this bill does accomplish some important reforms.”

Black called the bill “only our first step.”

Trump added on Twitter, “This is finally your chance for a great plan!”

Democratic Representative Debbie Wasserman Schultz, a breast cancer survivor, called the bill “an immoral piece of legislation” that would gut medical coverage and patient protections.

A Quinnipiac University poll released on Thursday found 56 percent of U.S. voters opposed the House bill, with only 17 percent supporting it. Quinnipiac said its poll had a margin of error of plus or minus 3 percentage points.

Replacing Obama’s signature health care plan was a key campaign pledge for Trump and Republicans, who view it as overly intrusive and expensive.

Obamacare boosted the number of Americans with health insurance through mandates on individuals and employers, and income-based subsidies. About 20 million Americans gained insurance coverage through the law.

The nonpartisan Congressional Budget Office said under the Republican legislation 14 million people would lose medical coverage by next year and more than 24 million would be uninsured in 2026.

The House plan would rescind a range of taxes created by Obamacare, end a penalty on people who refuse to obtain health insurance, end Obamacare’s income-based subsidies to help people buy insurance while creating less-generous age-based tax credits

It also would end Obamacare’s expansion of the Medicaid state-federal insurance program for the poor, cut future federal Medicaid funding and let states impose work requirements on some Medicaid recipients.

House leaders agreed to a series of last-minute changes to try to win over disgruntled conservatives, including ending the Obamacare requirement that insurers cover certain “essential benefits” such as maternity care, mental health services and prescription drug coverage.

The House and Senate had hoped to deliver a new healthcare bill to Trump by April 8, when Congress is scheduled to begin a two-week spring break.

Click on the links below for related graphics:

Graphic on Obamacare and Republican healthcare bill (http://tmsnrt.rs/2n0ZMKf)

Graphic on shifting positions in the U.S. Senate on Republican healthcare bill (http://tmsnrt.rs/2mUE4Xf)

Graphic on poll on Americans’ views of the Republican healthcare bill (http://tmsnrt.rs/2n7f3e4)

(Additional reporting by Susan Heavey, Susan Cornwell, Jeff Mason, David Morgan, David Lawder, Amanda Becker, and Doina Chiacu; Writing by Will Dunham; Editing by Bernadette Baum and Bill Trott)