Republican U.S. Sen. Susan Collins is defending her vote on tax legislation by claiming she has an “ironclad” commitment from lawmakers that the bill won’t result in Medicare cuts.

House and Senate negotiators are tasked with working out differences on a tax overhaul bill after the Senate approved its version on a 51-49 vote early Saturday.

Collins told NBC’s “Meet the Press” on Sunday she supported the tax bill after inclusion of her amendments on medical expense and property tax deductions.

Economists believe the tax changes will increase debt, but Collins says she spoke to several who believe the bill will spur enough economic growth to offset the reduced tax rates and will lower debt.

Maine’s Sen. Angus King told CBS’s “Face the Nation” that few lawmakers actually know what’s in the lengthy tax bill. And in a statement issued over the weekend, King, an independent who caucuses with the Democrats, decried the bill, in part, for benefiting the wealthy at the expense of others.

“Rather than maximize this opportunity to help working Americans and set our nation on a path to further prosperity, this bill pushes through at least $1 trillion in unfunded tax cuts for the wealthy and for corporations,” King stated.

Members of Brunswick Area Indivisible and Harpswell Indivisible said they gathered Saturday on the Brunswick Mall to protest against Collins’ vote while praising King.

“Although Sen. Collins has said repeatedly that a bill of this magnitude should pass through regular order, this bill passed with only 50 Republican votes, in the middle of the night, with many changes written into the margins even as it was being printed,” according to a statement issued by Brunswick Area Indivisible. “This bill shifts the tax burden to the middle class and poor, gives billions in benefits to the wealthiest, and harms our children. It’s a sad day for Maine.”

Maine 1st District Congresswoman Chellie Pingree, a Democrat, who opposed the House version of the bill, also decried the Senate version, using the hashtag #GOPTaxScam on Twitter.

Maine 2nd District Congressman Bruce Poliquin, a Republican who supported the House version of the bill, said he supported amendments by Collins in the Senate bill, which he said will “benefit Maine families and small businesses, such as retaining the medical expense deduction and improving the provision dealing with historic tax credits.”

Poliquin wrote: “Sen. Collins and I have both said there are problems with Obamacare, the Affordable Care Act, that we need to fix, and I’m pleased this new law starts to fix those problems.”

THE ASSOCIATED PRESS contributed to this report.