(Bloomberg) -- A key GOP holdout on the party’s health-care bill said Wednesday that he wouldback the measure, saying he thinks an amendment he proposed may beenough to win passage in the House later this week.

Representative Fred Upton of Michigan told reporters at theWhite House after a meeting with President Donald Trump that he’sready to vote for the bill once a new amendment he helped devise isadded that would boost funding for people with pre-existing conditions.

"I think it is likely now to pass in the House," Upton said.Republican Representative Billy Long of Missouri, another holdout,also said he’s ready to back it.

A senior House Republican with knowledge of the vote-countingsaid Wednesday that the pair’s reversal gets the GOP closer tohaving the votes for passage, but they’re not there yet.

A White House official said Republicans are still two or threevotes away from being able to guarantee passage, adding that theconservative House Freedom Caucus can accept the new amendment.

Moderates still opposed

But several moderates, including Representatives Charlie Dent ofPennsylvania, Leonard Lance of New Jersey and Ileana Ros-Lehtinenof Florida said Wednesday they remain opposed even with the latestchanges.

"I’m still a no," Lance said, adding Upton’s amendment isn’tenough to resolve his concerns about coverage for people withpre-existing conditions.

Even so, the reversals by Upton and Long give new energy to theGOP’s bill, which appeared to be short of the votes needed forpassage, with a number of moderates opposed.

Since no Democrats are expected to vote for the bill,Republicans can only lose 22 Republicans if everyone in the Housecasts a vote.

Even if the bill makes it out of the House, it remains wellshort of the 50 votes it would need in the Senate. A number ofsenators are unhappy with an earlier Congressional Budget Officeestimate showing it would result in 24 million more people withoutinsurance within a decade and skyrocketing premiums forlower-income people, particularly those over the age of 50.

At least eight Senate Republicans have expressed significantreservations about different elements of the bill, including therecent changes related to pre-existing conditions, and GOP leaderscan only afford to lose two votes.

White House optimism

The White House earlier signaled optimism, with budget directorMick Mulvaney telling Fox News on Wednesday that the chamber mightvote on the health bill as early as Saturday. Mulvaney said hebelieves the amendment by Upton -- who became perhaps the mostsignificant Republican defection yet on Tuesday -- will help drawmoderates’ support for the legislation.

Upton’s amendment would provide $8 billion over five years toreduce premiums and other costs for those with pre-existingconditions who have a gap in coverage and reside in states thatreceived waivers from some of Obamacare’s requirements underanother provision in the bill.

Democrats immediately blasted the change, with Senate MinorityLeader Chuck Schumer saying: “The proposed Upton amendment is likeadministering cough medicine to someone with stage 4 cancer."

AARP, the influential lobby that advocates for older Americans,says it remains opposed to the GOP bill, posting in a tweetthat the Upton amendment is an "$8 billion giveaway to insurancecompanies; won’t help majority of those w/preexistingconditions."

Other Republicans haven’t seen details or text of the amendment,but health-care experts said the added funding is unlikely to makea big difference, unless very few states receive those waivers.

The $8 billion in funding is a “drop in the bucket,” said MattFiedler, a fellow at the Brookings Institution’s Center for HealthPolicy. He said the money, even including the bill’s stability fundand risk-pool funding, wouldn’t be enough to fully protect peoplewith pre-existing conditions from facing higher costs.

The Center for American Progress, a progressive think tank inWashington, estimated that the Republican health bill, whichincludes about $130 billion over 10 years that could be usedto help low-income Americans with pre-existing conditions, wouldfall about $20 billion short annually.

About 27 percent of adults have a pre-existing condition likecancer or heart disease that insurers refused to cover beforeObamacare, said Larry Levitt, senior vice president for specialinitiatives at the Kaiser Family Foundation.

“There are millions with pre-existing conditions,” he said.

The latest efforts come after Ryan told Republicans Tuesday to“pray” as they try to win over holdouts. Representative Dennis Rossof Florida, a senior member of the House vote-counting team,described Republicans’ closed-door meeting and said they were about“five votes away” from the number needed to pass the bill.

Representative Phil Roe of Tennessee said Tuesday that GOP Housemembers plan to hold a closed-door meeting Thursday to decidewhether to proceed with a vote this week.

Upton Amendment

Upton’s defection was significant because until last year, hewas chairman of the Energy and Commerce Committee, which hasjurisdiction over much of health-care policy, and he has been astaunch supporter of Obamacare repeal.

Voters have confronted lawmakers at town hall-style meetingsacross the U.S. in recent weeks with their concerns about losinghealth insurance under the GOP plan, giving some moderateRepublican lawmakers jitters about backing the measure.

Yet party leaders have pushed to create a sense of urgency amongtheir members to make good on a years-long promise to repeal formerPresident Barack Obama’s signature health-care law now thatRepublicans control Washington.

‘Now is the time’

“Now is the time,” House Majority Leader Kevin McCarthy toldHouse Republicans on Tuesday, adding that they should be preparedto vote Wednesday or Thursday on the measure.

Ryan also tried to boost the pressure on Republican moderates toadvance the bill. “This is who we are. This will define us,” thespeaker told Republicans, according to Ross.

Upton on Tuesday cited the bill’s provision on pre-existingconditions as a reason for his defection. Under the bill -- priorto the amendment he is now working on -- states could allowinsurers to charge higher premiums for people with pre-existingconditions who have had a gap in coverage of at least 63 days inthe prior year. States could also let insurers charge oldercustomers more than the original bill allowed -- at least fivetimes more than younger ones, beginning in 2018.

“I told the leadership I cannot support the bill with thisprovision in it,” Upton said Tuesday. “It’s not going to get my‘yes’ vote the way it is.”

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