WASHINGTON — Days before a pivotal vote, House Speaker Paul Ryan said Sunday he will seek changes to a Republican health care bill to provide more help to older people. The new willingness to compromise was a bid for more support from moderate Republicans, who expressed continuing unease about the plan to replace President Obama’s health law unless significant changes were made.

Ryan insisted that he felt “very good” about the bill’s prospects but acknowledged that House leadership was “making fine-tuning improvements to the bill to reflect people’s concerns.”

Paul Ryan

A House vote was scheduled for Thursday.

“We believe we should have even more assistance. And that’s one of the things we’re looking at for that person in their 50s and 60s because they experience higher health care costs,” the Wisconsin Republican said.

Under the Republican plan, older people who are not yet eligible for Medicare stand to be the biggest losers. It would shrink the tax credits they use to help buy insurance and it would increase their premiums because the bill allows insurers to charge more as people age and become more susceptible to health problems.

A Congressional Budget Office analysis last week said a 64-year-old with income of $26,500 would pay $1,700 out of pocket for insurance under the Affordable Care Act, compared with $14,600 under the Republican plan. It estimated that 24 million people of all ages would lose coverage over 10 years.

On Sunday, Ryan said he believed the CBO analysis was not accurate because Obamacare wouldn’t be able to last 10 years. But he allowed the additional assistance was one of several House revisions to be discussed in advance of Thursday’s vote, along with possible changes to help low-income people more with tax credits and require able-bodied Medicaid recipients to meet work requirements.

“We think that we should be offering even more assistance than what the bill currently does,” he said.

Health and Human Services Secretary Tom Price also said legislative revisions were possible.

“If it needs more beefing up … for folks who are low income, between 50 and 64 years of age, that’s something that we’ve talked about, something that we’ve entertained, and that may happen throughout the process,” he said.

Their comments came as President Trump and House leaders seek to win support from Republican skeptics as prospects for the bill remain wobbly. Last week, Trump agreed to add fresh Medicaid curbs to appease some conservatives. But moderate Republicans are balking over the CBO’s findings that millions more people would lack coverage even while premiums in many cases could rise.

In a Facebook post Saturday night, Rep. Brian Fitzpatrick, a Pennsylvania Republican, said he couldn’t vote for the bill, stressing a need “to take our time and to get this right.”

In the Senate, where Republicans hold a narrow 52-48 majority, prospects for the bill also were uncertain as both moderates and conservatives criticized it.

Sen. Susan Collins, R-Maine, said she would not vote for the measure without additional changes to provide more aid to older Americans. She also wants an improved proposal that would cover more Americans and offer better Medicaid benefits than the current GOP plan. She joins at least four other GOP senators in opposing the bill after conservative Sen. Ted Cruz of Texas said Sunday he wouldn’t vote for it as is.

Sens. Dean Heller of Nevada, Mike Lee of Utah and Rand Paul of Kentucky are also opposed.

“I cannot vote for any bill that keeps premiums rising,” Cruz said.

Separately, Ryan said he also expected the House to make changes to Trump’s proposed budget, which calls for a boost to military spending but big-time cuts in domestic programs. Trump’s plan, for instance, would cut $5.8 billion from the National Institutes of Health, an 18 percent drop for the $32 billion agency that funds much of the nation’s research into what causes different diseases and what it will take to treat them.

Ryan said Congress was proud to have passed the Cures Act last year, which calls for additional NIH money for “breakthrough discoveries on cancer and other diseases,” so he expects the proposed NIH cut to be revised.

“I would say, this is the very, very beginning of the budget process,” he said. “We are encouraged that we’re seeing an increase in defense because we think our military has been hollowed out. But I will say that NIH is something that’s particularly popular in Congress. … So, that is something that I think in Congress you’ll see probably some changes.”

Ryan spoke on “Fox News Sunday,” Price appeared on ABC’s “This Week,” Collins was on NBC’s “Meet the Press” and Cruz spoke on CBS’ “Face the Nation.”