U.S. Sen. Susan Collins is backing a proposal that would require people to provide proof of U.S. citizenship when registering to vote and photo ID in order to cast ballots in federal races.

The Republican-led bill, known as the Safeguard American Voter Eligibility (SAVE America) Act, passed the House of Representatives largely along party lines last week and comes as President Donald Trump has called for a nationalization of elections.

It now advances to the Senate, where it faces dim prospects given that at least one Republican, Sen. Lisa Murkowski of Alaska, has expressed concerns and Senate Majority Leader John Thune has said he won’t lower the 60-vote filibuster threshold to bring the measure to a vote.

Trump has indicated he may pursue an executive order to implement national voter ID requirements if the bill doesn’t get through Congress.

Collins, a Republican who backed a similar measure last year, said in a written statement Monday that she supports the bill that recently passed the House, though she does not support elimination of the filibuster rules.

“The law is clear that in this country only American citizens are eligible to vote in federal elections,” Collins said. “In addition, having people provide an ID at the polls, just as they have to do before boarding an airplane, checking into a hotel, or buying an alcoholic beverage, is a simple reform that will improve the security of our federal elections and will help give people more confidence in the results.”

Collins said she opposed a previous version of the bill that would have required people to prove citizenship every time they cast a ballot, saying that would place an unnecessary burden on voters.

The measure comes after Maine voters in November rejected a referendum to require people to present photo ID when voting by a margin of 64% to 36%.

Democrats running to challenge Collins for her seat this year criticized her position, saying the proposal would make it harder for people to vote.

“Susan Collins is once again appeasing Republican leadership and caving to pressure by backing a dangerous Trump-backed voter suppression bill that will disenfranchise voters across Maine and America,” Gov. Janet Mills said in a written statement over the weekend.

“Susan Collins is painfully aware that voter suppression is her only chance to stay in office,” Sullivan oyster farmer and veteran Graham Platner said in a post on social media.