The White House expressed optimism Friday afternoon that the Republican-backed health care bill would pass the House despite speculation it was short of support ahead of an afternoon vote demanded by President Trump.

White House press secretary Sean Spicer said Trump is looking forward to the House passing the bill and confirmed House Speaker Paul Ryan is meeting with Trump to “discuss the way forward” on the bill.

According to GOP lawmakers and congressional aides, House Republican leaders were short of the votes needed for the bill to pass.

Trump on Friday told lawmakers still on the fence over repealing and replacing ObamaCare with TrumpCare, that voting against the White House-backed bill is tantamount to voting for Planned Parenthood.

Trump tweeted Friday, “The irony is that the Freedom Caucus, which is very pro-life and against Planned Parenthood, allows P.P. to continue if they stop this plan!"

In a bid to coax support from conservatives, House leaders proposed a fresh amendment repealing Obama's requirement that insurers cover 10 specified services like maternity and mental health care.

Conservatives have demanded the removal of those and other conditions the law imposes on insurers, arguing they drive up premiums.

The president met with members of the Freedom Caucus Thursday in an effort to win them over. But the vote was postponed after administration officials fell short.

Trump issued lawmakers an ultimatum Thurday night. He wants the House to vote Friday on the legislation to begin dismantling ObamaCare and if it fails, he is "done with health care,” and ready to move on to tax reform, a source told Fox News.

"My understanding is he’s going to get it," White House Press Secretary Sean Spicer said on "The O'Reilly Factor."

"We’re hoping to make this the last anniversary that any American has to suffer under ObamaCare by instilling a patient-centric health care system in place, and the president has made that case to members throughout the spectrum of the Republican conference, and tomorrow, it’s time to vote," he added.

House Majority Leader Kevin McCarthy, R-Calif., thinks it will wrap up by 4:30 or 5 p.m. ET (WATCH FOX NEWS CHANNEL FOR COMPLETE COVERAGE). If the bill passes, it will be a monumental achievement for Speaker Ryan and Trump. But if the bill stumbles, recriminations will abound.

Trump's demands aren't sitting well with some Republicans.

Kentucky Republican Rep. Thomas Massie tweeted Friday morning:

"If Exec branch tells Legislative branch "when 2 vote" "how 2 vote" & "what it will b allowed 2 work on if vote fails," is that a republic?"

Republican leaders Thursday canceled a vote after leadership's attempts to lobby enough votes apparently failed -- a major setback for Ryan and Trump.

"For seven and a half years we've been promising the American people that we will repeal and replace this broken law because it's collapsing and failing families," House Speaker Paul Ryan told reporters after meeting with Republican leaders. "Tomorrow we're proceeding."

Trump and Republican leaders had spent much of the day scrambling to get both moderates and conservatives on board with the increasingly unpopular legislation.

"We have not gotten enough of our members to get to yes at this point under what we have now," House Freedom Caucus Chairman Mark Meadows, R-N.C., told reporters.

Ryan postponed his press conference twice as he worked with House Majority Leader Kevin McCarthy R-Calif., Majority Whip Steve Scalise, R-La., and Chief Deputy Whip Patrick McHenry, R-N.C., to get enough votes to get the American Healthcare Act through the House on the seventh anniversary of ObamaCare's passage.

The House Rules Committee is expected to prep the health care bill starting at 7am ET Friday.

When asked about the timing of the vote McCarthy told Fox News the House should be "done in the afternoon" but said Democrats could delay things.

Meanwhile, Trump met inside the Cabinet room with the Freedom caucus to try and rally conservatives to the cause. He also tweeted, urging supporters to call their representatives to back the bill.

A senior administration official told Fox News after the meeting with Trump and the conservative group that there was a deal in the works, but that it was not yet finalized. A source from the Freedom Caucus later said there wasn't yet a deal.

"I would say progress is being made, and that progress should be applauded with the efforts by the White House to deliver on a campaign promise, and to lower premiums for every American from coast to coast and in between," Meadows said. He also called Trump's involvement "unparalleled in the history of our country."

When asked if this was a loss for the president, Meadows said: "Absolutely not."

Earlier in the day, Spicer had expressed confidence that the White House was would be voted on and would pass.

"It’s going to pass. That’s it," he said at his daily press briefing.

Spicer also noted that Trump had been making calls past 11 p.m. Wednesday night to try and bring members on board.

Sources later told Fox News that the White House was anticipating a vote after midnight, but that was before the vote was canceled.

House Republicans were due to meet about the around 7 p.m. ET, but there appeared no clear path to pass the bill.

In appealing to conservatives with concessions that include limiting requirements that plans offer benefits including maternity and substance abuse care, Republican leaders risk scaring off moderates. A plan to cut funding to Planned Parenthood also risked spooking centrist Republicans.

Meanwhile, Democrats blasted what they saw as Republicans’ amateurish maneuvering. House Minority Leader Nancy Pelosi said it was a "rookie's error" to bring the legislation to a vote so early, and urged fellow Democrats to oppose the legislation.

“While Republicans scramble to make TrumpCare even more destructive, our Caucus must continue to be fully engaged today in exposing its disastrous consequences for the American people,” she told colleagues in a letter Thursday.

The AHCA would stop ObamaCare’s tax penalties against Americans who choose not to buy coverage, as well as cutting the federal-state Medicaid program for low earners. It would also give tax credits to help people pay medical bills, while allowing insurers to charge older Americans more. It would also repeal tax increases on high-earners and health companies.

Fox News' John Roberts, Mike Emanuel, Serafin Gomez, Chad Pergram and The Associated Press contributed to this report.