PORTLAND, Maine — U.S. Sen. Susan Collins said she is confident President Donald Trump and Senate Majority Leader Mitch McConnell will ensure passage of two bills aimed at shoring up the insurance markets, a demand she made before supporting the Republican tax overhaul.

The Senate version of the tax bill narrowly passed Saturday, and Republican leaders hope to deliver a final tax package to the president by Christmas. A House bill already had been approved.

Several Democratic and left-leaning groups say Collins, a Republican, traded her support for health care concessions that House Republicans could ultimately block.

The senator from Maine wants to give states $10 billion over two years to establish high-risk pools or reinsurance programs to lower premiums. She also is pushing a bill that would provide key payments to insurance companies for the next two years in exchange for more flexibility in how states administer the federal health care law, which Republicans have unsuccessfully sought to repeal.

Collins remains confident that Trump and McConnell, fellow Republicans, will keep their word and make sure the health care bills get approved, said Annie Clark, a spokeswoman for the senator.

Trump told Collins during a lunch last week that he supports the bills, Clark said. And McConnell committed in writing to support passage of the bills either before adoption of a final tax bill or before the end of the year, Clark said.

“She remains very confident in this commitment,” Clark said of McConnell’s promise.

Collins was criticized after telling NBC’s “Meet the Press” on Sunday that “economic growth produces more revenue, and that will help to offset this tax cut and actually lower the debt.”

She cited Glenn Hubbard, Lawrence Lindsey and Douglas Holtz-Eakin, conservative economists who recently signed a letter saying the tax bill will grow the economy.

Holtz-Eakin, former director of the Congressional Budget Office, said the bill would spur economic growth that could generate “some additional revenue.” But he said the growth would not be enough to offset the tax cut. Hubbard told the Washington Post he has not done a revenue estimate of the tax plan.

Offices for Hubbard and Lindsey said the economists were not available for comment this week.

Collins previously “put a lot of weight” on analyses by the Congressional Budget Office, said Topher Spiro, senior fellow at the Center for American Progress, a liberal think tank. “It’s disappointing that she’s pointing to a handful of very conservative economists who actually don’t even say that the tax cuts will more than pay for themselves,” Spiro? said.

Clark said the senator never said the tax cuts would pay for themselves and noted that the Joint Committee on Taxation projected the tax bill would stimulate the economy.

The joint committee concluded last week that, even with a bump in growth, the Senate tax bill as written would swell the national debt by $1 trillion over 10 years.