A proposed law to require candidates for U.S. president and vice president to make their tax returns public before they can qualify for the ballot in Hawaii might turn out to be unconstitutional, and lawmakers are putting the issue on hold for the moment.

The Senate Judiciary and Labor Committee deferred action last week on Senate Bill 150, which would impose the tax return disclosure requirement, while lawmakers search for some other way to pressure presidential candidates to publicly release their returns.

Donald Trump last year became the first Democratic or Republican nominee for president in more than 40 years to refuse to release his tax returns. During the campaign Trump said he was willing to release his returns, but said he was unable to do so because he was being audited by the Internal Revenue Service.

Last week Trump’s senior adviser, Kellyanne Conway, told the ABC television news program “This Week” that the president has no plan to release his returns now. Conway made those comments in response to questions about a petition on the Whitehouse.gov website signed by more than 200,000 people demanding that Trump release his returns.

Critics argue that Trump could encounter conflicts of interest as president because of his vast business holdings, and contend he should release his returns to help the public determine whether conflicts exist.

In Hawaii, SB 150 would require that candidates for president and vice president submit their most recent tax return to Hawaii’s chief election officer before they can qualify for the ballot here. According to the Tax Foundation of Hawaii, California, Massachusetts and New Mexico are all considering similar measures.

Hawaii Deputy Attorney General Deirdre Marie-Iha said it is an “open question” whether the proposed law would violate the U.S. Constitution. Marie-Iha cited a 1995 U.S. Supreme Court decision that found that qualifications for federal office are established exclusively in the U.S. Constitution, meaning that the states cannot impose additional requirements such as term limits.

Lawmakers including state Sen. Karl Rhoads, who introduced the measure, said they want to pursue the issue.

“It’s an extremely important office, and (releasing returns) does provide a lot of information about potential conflicts and it’s sort of a background check on whether you’re telling the story of your life accurately,” said Rhoads (D, Downtown-Nuuanu-Liliha). “For a position that important, I don’t think it’s unreasonable to ask for tax returns, and dozens of presidential candidates have provided them over the last 40 years, so they didn’t see it as unreasonable, either.”

The bill was supported by the League of Women Voters of Hawaii, Common Cause Hawaii and Americans for Democratic Action Hawaii but was opposed by the Libertarian Party of Hawaii. Libertarian Party Chairwoman Tracy Ryan said the voters should decide whether candidates are fit to hold office.

Senate Judiciary Chairman Gil Keith-Agaran on Tuesday deferred action on the bill until Feb. 28 to give Marie-Iha time to research the legal issues and help lawmakers rewrite the bill in a way that would satisfy the courts.

One possibility may be to pass a law mandating that members of the Electoral College from Hawaii may vote only for candidates who have publicly disclosed their tax returns, lawmakers said. The state generally has the authority to impose requirements on the Electoral College, Marie-Iha said, but it is uncertain whether the federal courts would find such a law acceptable.