A watchdog group is pushing Congress to pass a law that would require presidential candidates to publish a copy of their tax returns.

The Sunlight Foundation, a nonpartisan ethics group, argued Thursday that politicians who seek the presidency should be held to a "higher standard of transparency."

"Just as presidential candidates are required to submit personal financial disclosure forms to the Federal Election Commission, they could be required to submit their tax returns for public review," John Wonderlich wrote for the Sunlight Foundation. "An orderly, enforceable, rule-based process would let us skip the drama and doubts, and ensure access to what we already expect of our candidates: a reasonably clear view into their financial lives."

The push comes as presumptive Republican nominee Donald Trump dismisses public calls to release his tax returns. The real estate mogul has argued he legally cannot do so while he is being audited by the Internal Revenue Service, a claim the IRS itself has debunked.

Trump's move is a departure from decades of precedent from presidents stretching back to Jimmy Carter who have released their tax returns prior to their election, according to the Tax History Project.

The returns of Trump's likely Democratic opponent, Hillary Clinton, have already been public for years given her husband's presidency and her own turns as a senator and as the secretary of state.

Critics have questioned whether Trump's returns contain unflattering details. For instance, some have speculated that the disclosure could reveal the candidate is less wealthy than he has claimed to be.

Trump has taken fire from both sides of the aisle for his refusal to release his returns.

Mitt Romney has served as a particularly vocal critic of the decision to withhold the tax forms pending the results of an audit, calling it a "disqualifying" move and hinting that Trump is hiding a " bombshell of unusual size."

"The public interest in tax return disclosure is only getting greater as candidates increasingly represent massive networks of corporate, nonprofit and political power," Wonderlich wrote. "This is even more pressing when one considers that the president is explicitly exempted from many of our conflict of interest laws."