Senator Ron Wyden, D-Ore., the ranking Democrat on the Senate Finance Committee, introduced legislation Wednesday requiring President-elect Donald Trump to release the three most recent years of his tax returns.

Several other Senate Democrats joined Wyden in introducing the bill, known as the Presidential Tax Transparency Act, which would also require future presidential nominees to release three years of tax returns.

Other original cosponsors include Senators Elizabeth Warren of Massachusetts, Tim Kaine of Virginia (Hillary Clinton’s vice presidential running mate), Dianne Feinstein of California, Ben Cardin of Maryland, Jeff Merkley of Oregon, Chris Murphy of Connecticut, Debbie Stabenow of Michigan, Tammy Baldwin of Wisconsin, Michael Bennet of Colorado, and Tom Udall of New Mexico.

The bill would require all sitting presidents to release their most recent three years of tax returns to the Office of Government Ethics. Within 15 days of becoming the nominee at the party convention, presidential nominees would need to release their most recent three years of tax returns to the Federal Election Commission if the bill passes, which is unlikely in the Republican-dominated Congress. If the sitting president or future candidates refused to comply, the Treasury Secretary would be required under the legislation to provide the tax returns directly to the Office of Government Ethics or the Federal Election Commission, respectively, for public release.

Trump’s refusal to release his tax returns became a hotly contested issue during last year’s presidential election. Trump’s tax attorneys claimed his tax returns had been under “continuous examination” by the Internal Revenue Service since 2002. Trump declined to release any of the returns, even those that were no longer being audited, claiming they were linked with the ones still under audit. Democrats, including rival Hillary Clinton, countered that nothing prevented him from releasing the returns, as presidential candidates have done ever since the Nixon administration.

“The fact that the president-elect refuses to release his tax returns is a tragic failure of transparency, and it needs to be corrected,” Wyden said in a statement Wednesday. “With President-elect Trump flouting bipartisan traditions of disclosure while engaging with foreign leaders at the highest level, it’s more important than ever to ensure that the Commander-in-Chief isn’t playing by a different set of rules.”

Michael Cohn, editor-in-chief of AccountingToday.com, has been covering business and technology for a variety of publications since 1985.