The presidential election has come and gone but U.S. Sen. Chris Murphy, D-Conn., hasn't given up on his fight to get Donald Trump to relase his tax returns.

Murphy and U.S. Sen. Ron Wyden, D-Ore., reintroduced the Presidential Tax Transparency Act this week, which would require sitting presidents and presidential nominees to release their last three years of tax returns. If they refuse, the U.S. Secretary of Treasury would be compelled to release them.

Trump, the president-elect, bucked a near-40 trend when he refused to release his tax returns during the campaign. Some top Republicans joined Democrats in calling on Trump to release the documents, but the bill remains unlikely to get much traction in the Republican-controlled Senate.

During the campaign, Trump said he wouldn't release his recent returns until the Internal Revenue Services completed an audit. Critics speculated that Trump is delaying the release because the documents could show that he pays little or no taxes, makes few charitable donations, isn’t as wealthy as he claims or that he has substantial foreign investments.

“Americans deserve to know if the President of the United States is making decisions on behalf of the citizens of this country or to protect his own investments,” Murphy said in a written statement. “The presidency is the most powerful position in the world – with the stroke of a pen the President can lift or impose sanctions, affect federal contracts, or influence foreign government actions. The person sitting in that office shouldn’t be hiding anything about his or her financial interests.”