The Washington state Senate passed a bill this week that would bar President Trump from the 2020 state ballot if he still has not made his tax returns public.

The bill, which would require any presidential candidate to release five-years-worth of tax returns before they can appear on the ballot for any primary or general election, advanced to Washington’s House of Representatives on Tuesday.

According to CBS News, lawmakers voted 28-21 to approve the bill. Although the bill’s sponsors believe it to be constitutional, there’s a good chance it will be challenged in federal court.

Democrats say the bill is necessary to prevent the prospect of Trump’s refusal to release his tax returns from becoming the norm.

“Although releasing tax returns has been the norm for about the last 40 years in presidential elections, unfortunately we’ve seen that norm broken,” Washington Senator Patty Kuderer (D) said, according to CBS News.

But according to Republicans, the bill is attempting to impose rules on a federal election, which crosses into risky territory.

“We’re on really risky ground when we’re trying to place conditions on a federal election,” GOP Senator Hans Zeiger said.

Trump has continually defied a decades-old tradition of presidents who have voluntarily made their tax returns public in the interest of transparency, claiming that he can’t do so because they are “under audit.”

“I’m under a routine audit and it’ll be released, and as soon as the audit is finished it will be released,” he said in 2017.

Lawmakers hope that making Trump’s returns public will answer long-sought after questions about his finances, which include any potential conflicts of interest, how he benefitted from his recent tax cut — and if he is indeed under audit for as long as he’s claimed.

“The tax returns are the key to finding out what this guy is all about,” Rep. Bill Pascrell (D-NJ) said earlier this month.

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