Maine Republican Sen. Susan Collins says she’s backing the SAVE Act.

The version of the bill passed in the House would require proof of U.S. citizenship when registering to vote and a photo ID to cast a ballot in federal races.

In a statement on Monday, Sen. Collins said she supports the bill saying it’s a simple reform that will improve election security.

Over the weekend, Gov. Janet Mills, who’s running to unseat Sen. Collins, accused her of caving to pressure in favor of a bill she says would disenfranchise voters in Maine and across the country.