(CNN) With special counsel Robert Mueller's investigation into Russian interference in the 2016 election now over, some House Democrats are getting increasingly antsy about efforts to get a look at President Donald Trump's tax returns.

"It's long past time" to get Trump's returns, Democratic Texas Rep. Lloyd Doggett, a member of the Ways and Means Committee, told CNN's Lauren Fox and Ellie Kaufman on Tuesday. That sentiment was echoed by New Jersey Rep. Bill Pascrell, another Ways and Means Democrat who has been outspoken about his frustration that committee chair Rep. Richard Neal (Massachusetts) has not yet set the wheels in motion on obtaining Trump's taxes.

Neal's ability to request Trump's taxes comes from a previously little-known law passed in the 1920s that says that the chairman of the House Ways and Ways Means Committee can request any individual's tax return, and the law says the secretary of the Treasury "shall" turn it over. Treasury Secretary Steven Mnuchin has made clear he has no plans to turn over any of Trump's returns if and when Neal makes the formal request, which Neal has not yet done. And House Republicans have insisted that Democrats' motives in all of this are simply to score political points off Trump in advance of the 2020 election and, therefore, should not be granted access to the returns.

Assuming Neal makes the formal request and Mnuchin refuses to turn the tax returns over, the likeliest outcome is a high-stakes court fight that could well land the issue before the Supreme Court right smack-dab in the middle of the 2020 presidential election. The likes of Pascrell and Doggett want to get that process started -- particularly now that the Mueller investigation is over and, according to Attorney General William Barr's summary of the report, neither Trump nor anyone in his campaign conspired or coordinated with the Russian government to help Trump win the 2016 election.

Neal has been much more plotting -- and plodding -- about all of this. "We are doing our due diligence," Neal told CNN earlier this month . "I don't have a timeline."

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