White House officials are willing to consider changes to the Republican healthcare bill if it could help it attract several of the centrist members who have held out since conservatives negotiated an amendment aimed at curbing Obamacare regulations.

"We are open to ideas that will strengthen the bill and get it over the finish line," a White House official told the Washington Examiner on Tuesday.

House Republicans are discussing changes to Obamacare reform legislation that would strengthen consumer protections for people with pre-existing conditions amid uncertainty over the number of lawmakers who will support the bill in its current form.

As leadership has worked to line up the 217 votes needed to advance an amended version of the American Health Care Act, centrist Republicans have balked at backing legislation they argue could effectively price sick constituents out of the insurance market.

"I can't imagine they force members to vote on something that doesn't have pre-existing condition coverage," an aide to an undecided Republican member told the Washington Examiner. "I don't know how they're going to do it this week."

That aide said the White House will likely struggle to drum up the necessary support for healthcare reform without first addressing the effect recent changes to the AHCA would have on sick peoples' premiums.

"I think that they're going to have a hard time, it's a hard sell without the pre-existing conditions coverage," the aide said.

Conservatives argue that allowing states to opt out of the regulations will lower premiums overall and increase access to health insurance while still leaving in place many protections for people with pre-existing conditions that did not exist before the 2010 healthcare overhaul.

A House Freedom Caucus source said the White House had promised conservative members that the bill would not undergo any additional changes at this point.

"Any changes to the substance of the bill at this stage would risk losing a large block of voters," the source said. "The votes are close. Now is the time to whip support, not make last minute changes and risk losing members en masse."

Even so, a White House source noted the administration has always indicated the bill could still be tweaked and said no group was promised otherwise.

A deal negotiated by Rep. Mark Meadows, chairman of the House Freedom Caucus, and Rep. Tom MacArthur, chairman of the centrist Tuesday Group, would preserve most Obamacare regulations but could allow states to opt out of some if those states could prove that premiums would not rise for people with pre-existing conditions. Those people would be covered in a "high-risk pool" along with other sick customers, allowing the market to stabilize for the overwhelming majority of people who are healthy.

Discussions among lawmakers Tuesday appeared to focus on a potential change to the bill that would provide more subsidies for those high-risk pools. The Freedom Caucus source said it was "hard to say" whether such a change would alienate conservative members.

"I'd guess it depends on the amount," the source said. "If it's not a large amount, most would still be yes."

Meadows and MacArthur settled on the concept of granting Obamacare waivers to states after the original version of the AHCA failed to attract enough support from conservatives to advance. Although their amendment brought nearly all Freedom Caucus members on board with the bill, centrist Republicans in competitive districts have bristled at the changes.

And House leadership expressed frustration Monday with the White House's unequivocal optimism that the healthcare legislation was ready to be brought to the floor for a vote, with one GOP aide calling the administration's prediction of an imminent vote "bizarre" given that the White House whip count has been "consistently wrong" when it comes to healthcare.

Vice President Mike Pence has already spent hours on Capitol Hill this week working to line up votes for the legislation.

It was unclear whether Pence is involved in talks to increase funding for high-risk pools.

A spokesman for Pence did not immediately respond to a request for comment.