WASHINGTON — President Trump and the Republican National Committee filed a pair of lawsuits on Tuesday against officials in California, challenging a new law requiring presidential candidates to release five years of tax returns in order to be placed on the state primary ballot in 2020.
The R.N.C. suit, which was filed in the Eastern District of California and included the California Republican Party and several California Republican voters as plaintiffs, called the law a “naked political attack against the sitting president of the United States.” It was filed against Gov. Gavin Newsom and the California secretary of state. Mr. Trump and his campaign filed a second suit challenging the constitutionality of the new law, and it named the California secretary of state and the state attorney general.
The law, known as the “California Presidential Tax Transparency and Accountability Act,” was signed by Mr. Newsom last week, and was the latest flash point between the White House and the State of California, which is involved in more than 40 lawsuits against the Trump administration, on issues including environmental regulation and immigration.
The California State Legislature approved a similar measure in 2017, but the governor at the time, Jerry Brown, vetoed it, raising questions about whether it was constitutional.
The suits filed Tuesday claim that the law would suppress the votes of millions of Californians who want to vote for Mr. Trump by adding a new requirement for a presidential candidate. The R.N.C. suit asserts that Mr. Newsom was creating an “extra-constitutional qualification for the office of president.” The suit argues that Democratic-controlled state legislatures were challenging Mr. Trump because they were “enraged” by his 2016 victory, when he did not disclose his federal tax returns.
The two lawsuits followed a complaint filed in Sacramento on Monday by Judicial Watch, a conservative group, on behalf of four California voters, seeking to block the law on constitutional grounds.
A spokesman for Mr. Newsom did not immediately respond to a request for comment. But, last week, he said states had 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.”
The vast majority of presidential nominees over decades have released their tax returns, with the exception of President Gerald Ford in 1976. Mr. Trump’s decision not to release his tax returns was one of the early traditions he shattered. But Mr. Newsom’s attempt to codify the tradition of disclosure into a law has raised serious constitutional issues, according to legal scholars.
“What other kinds of regulations can one imagine that states might impose on presidential candidates to get onto the ballot?” said Richard M. Pildes, a professor of constitutional law at New York University.
In a statement, Ronna McDaniel, chairwoman of the R.N.C., said that “it certainly doesn’t bode well for Democrats heading into 2020 that their best bet for beating President Trump is to deny millions of Californians the ability to vote for him.”
She called it a “stunt” that was “unconstitutional and, simply put, desperate.”
Jay Sekulow, counsel to Mr. Trump and to the campaign, called the campaign’s lawsuit a “decisive action in federal court challenging California’s attempt to circumvent the U.S. Constitution.” He said “the issue of whether the president should release his federal tax returns was litigated in the 2016 election and the American people spoke.”