WASHINGTON — Senator Ron Wyden, Democrat of Oregon, introduced legislation on Wednesday that would require major presidential candidates to publicly disclose their three most recent personal income tax returns, a challenge to the presumptive Republican nominee, Donald J. Trump, who has resisted releasing his filings.

Mr. Wyden, the ranking Democrat on the Senate Finance Committee, is trying to goad Republicans, including the committee chairman, Senator Orrin G. Hatch of Utah, and the majority leader, Senator Mitch McConnell of Kentucky, into defending Mr. Trump, giving Democrats a legislative rallying point.

But Mr. McConnell and Mr. Hatch, as leaders of the majority, are likely to ignore the bill.

Mr. Wyden’s measure, called the Presidential Tax Transparency Act, would apply to Democratic and Republican candidates, but both of the Democratic candidates, Hillary Clinton and Senator Bernie Sanders of Vermont, have disclosed their tax returns.