Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

House Republicans are preparing to hold a vote on their health care bill this week as they continue to work on convincing waffling members to support it, congressional aides tell NBC News.

In another sign that Republicans could get to a vote soon, Rep. Jason Chaffetz, R-Utah — a much-needed supporter in what is shaping up to be very tight vote — is planning to return to Washington Tuesday after undergoing foot surgery that was supposed to keep him sidelined for a few weeks, according to a source familiar with his plans.

Republicans are growing more confident that they are nearing enough votes to pass the measure in the House after changes were announced last week to the bill that brought a bloc of conservative members on board.

"I think we have the votes," said Rep. Joe Barton, R-Texas, told reporters leaving a meeting with Vice President Mike Pence in the Capitol Monday evening. "It's going to happen - it's going to happen."

An email sent to House Republicans of the week’s schedule included a note in bright red font that stressed attendance for votes this week is incredibly important, according to an aide.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Related: Both Parties Claim Wins in Rare Bipartisan Budget Deal

The American Health Care Act, a bill to repeal and replace the Affordable Care Act, was shelved more than a month ago after there weren’t enough votes to pass it.

Negotiations continued, however, and changes to the bill authored by Rep. Tom MacArthur, R-N.J., helped to convince members of the House Freedom Caucus to support it.

But when Republicans gained conservatives, they lost moderates.

NBC’s whip count shows 20 Republicans firmly against the bill. Another dozen are undecided. They can only lose 22 votes or else the bill will fail as it is expected to garner no Democratic support.

Members of leadership and MacArthur are lobbying GOP members who remain skeptical due to concerns that it will gut coverage for people with pre-existing conditions and reduce benefits for others. The bill’s authors insist that is not the case.

“This is to the point where it’s about one-on-one conversations between leadership and individual members who are working to get to yes and those will continue through the beginning of this week,” a top Republican aide told NBC News

The compromise amendment to the larger bill allows states to ask for a waiver from providing a robust benefits package currently mandated in Obamacare, such as maternity care and emergency care. If a state got a waiver, it would also allow people with pre-existing conditions to be charged more, which Obamacare currently doesn’t allow. Some fear that those changes gut important patient protections that the Affordable Care Act offered.

For his part, Trump is giving mixed messages. He told CBS News' "Face the Nation" on Sunday that pre-existing conditions are protected in the bill.

"Pre-existing conditions are in the bill. And I mandated it. I said, 'Has to be,'" Trump said.

The president then he told Bloomberg News on Monday that it will be in a final version of the bill.

“I want it to be good for sick people. It’s not in its final form right now," he said. "It will be every bit as good on pre-existing conditions as Obamacare."