President Trump and the Republican National Committee filed two lawsuits Tuesday against California officials challenging a new law that would bar Trump from appearing on the state’s primary ballot next year if he declines to disclose his tax returns.

The federal lawsuits, which were threatened last week when Gov. Gavin Newsom (D) signed the bill into law, argue that the measure requiring presidential and gubernatorial candidates to release five years of tax returns runs afoul of the U.S. Constitution.

The RNC suit, which includes the California Republican Party as a plaintiff, alleges a “naked political attack against the sitting president of the United States.”

Newsom responded on Twitter to the lawsuits filed in U.S. District Court in Sacramento, writing: “There’s an easy fix Mr. President — release your tax returns as you promised during the campaign and follow the precedent of every president since 1973.”

Trump broke with decades of tradition during the 2016 election by not voluntarily releasing his tax returns. His administration has rebuffed efforts by the Democratic-led House to obtain the documents from the Internal Revenue Service.

California’s primaries are scheduled for March 3, the day known as Super Tuesday because of the large number of delegates at stake.

Both lawsuits filed Tuesday argue that the California law illegally added a new constitutional requirement for eligibility for office.

In a tweet, RNC Chairwoman Ronna McDaniel chided Democrats for passage of legislation that might inspire other Democratic-led states to follow suit.

“It certainly doesn’t bode well for Democrats heading into 2020 that their best bet for beating @realDonaldTrump is to deny millions of Californians the ability to vote for him,” she said. “This stunt by Democrats is unconstitutional and, simply put, desperate.”

In a statement, Jay Sekulow, Trump’s personal attorney, said he was confident that the president would prevail in court, claiming that California was attempting to “circumvent the U.S. Constitution.”

“The issue of whether the president should release his federal tax returns was litigated in the 2016 election and the American people spoke,” he said.

In a statement made when he signed the legislation into law last month, Newsom said that given its size, California has “a special responsibility to require this information of presidential and gubernatorial candidates.”

“These are extraordinary times and states have a legal and moral duty to do everything in their power to ensure leaders seeking the highest offices meet minimal standards, and to restore public confidence,” he said.

If the law stands, the implications for Trump are unclear. Absent the emergence of a credible Republican primary challenger, he could opt not to appear on California’s ballot and still win the nomination.