In a snap ruling from the bench, U.S. District Judge Morrison England of the Eastern District of California on Thursday temporarily blocked a new California law requiring presidential candidates to disclose five years of tax returns to appear on the 2020 primary ballot.

The tentative ruling followed a free-wheeling, two-hour hearing over a request by President Donald Trump's campaign and Republicans at the state and federal law for a preliminary injunction. Lawyers arguing the case were preparing to leave the courtroom at the end of arguments when England told everyone to wait and then announced how he intended to rule.

England did not offer specific reasons for his initial decision but said he would issue a final ruling by Oct. 1. He said the timeline would allow attorneys on both sides to prepare for an inevitable appeal. The case is one of several in courts around the country where Trump is fighting to keep his financial information secret. On Thursday, Trump's lawyers sued New York prosecutors to stop their demands for eight years of tax returns.

England had peppered lawyers for California with questions about the law, which, while applying to presidential and gubernatorial candidates, was openly aimed by California leaders at Trump, who has refused to reveal his taxes. Trump, defying modern custom of presidential candidates releasing tax returns, has blamed an ongoing audit. But critics contend nothing would stop him from disclosing his tax returns.

The judge questioned whether California's law is preempted by federal law, the Ethics in Government Act, that requires certain financial disclosures by presidential candidates. He also expressed doubt about the law's compliance with the Constitution's qualifications clause and suggested allowing California to set specific standards for candidates would lead to "a hodge podge" of different requirements by states.

Harmeet Dhillon, one of seven attorneys who appeared for plaintiffs in five consolidated cases, said she was pleased with the ruling but "until I get that hot final document, whatever it is, in my hands, I'm not going to count my chickens."

England did ask lawyers for Trump and other Republicans whether the state did not have a genuine interest in providing a candidate's information to voters. Consovoy McCarthy partner Thomas McCarthy, representing the president and his campaign, called the requirement a "severe burden" to candidates and those considering running for office. McCarthy quoted former California Gov. Jerry Brown, who vetoed a previous version of the bill signed by Gov. Gavin Newsom this year, calling it a bad precedent.

Democratic State Senator Mike McGuire, the author of the legislation, said in an email statement Thursday afternoon that the judge's decision was "perplexing, premature and not necessary."

"We're way out in front of any deadline required under the law and the irreparable harm argument is simply not apparent," McGuire said. "I think the judge got this one wrong and a decision as important as this should not have been rushed or the law prematurely shut down."

California leaders, unveiling and touting the new law over the summer, said leading constitutional law scholars and practitioners were supporting the measure.

"No other constitutional provision is implicated or violated by a state's requirement that a Presidential candidate disclose tax returns," David Boies of Boies Schiller Flexner said in a statement in July. "Moreover, California, which permits electors to be chosen by popular vote, has an important interest in insuring that its voters are informed."

Gibson, Dunn & Crutcher's Theodore Boutrous, a regular Trump critic who has sued the White House over media access, said the law applied across the board to any presidential candidate, not just Trump.