(Adds temporary stay by federal appeals court, Trump tweet, details from decision, background, byline)
By Jonathan Stempel
NEW YORK, Oct 7 (Reuters) - A federal judge on Monday said U.S. President Donald Trump must hand over eight years of tax returns to Manhattan prosecutors, forcefully rejecting the president's argument that he was immune from criminal investigations.
The decision by, U.S. District Judge Victor Marrero in Manhattan, further complicates Trump's battle to keep his finances under wraps, despite having promised during his 2016 White House run that he would disclose his tax returns.
Trump's immunity claim was "repugnant to the nation's governmental structure and constitutional values," Marrero wrote. "The court cannot square a vision of presidential immunity that would place the President above the law."
The president quickly appealed the decision to the federal appeals court in Manhattan, which in a brief order temporarily halted enforcement of the subpoena by Cyrus Vance, the Manhattan district attorney.
Vance, a Democrat, had subpoenaed personal and corporate tax returns from 2011 to 2018 and other records from Trump's longtime accounting firm Mazars USA, as part of a criminal probe into the president and his family business.
"The Radical Left Democrats have failed on all fronts, so now they are pushing local New York City and State Democrat prosecutors to go get President Trump," Trump, a Republican, tweeted after Marrero's decision. "A thing like this has never happened to any President before. Not even close!"
Trump's lawyers had argued that the president was immune from such a probe while in office and that the Constitution required Vance to wait until after Trump left the White House.
The president is separately trying to block Deutsche Bank AG from handing over financial records, which the bank has said include tax returns, sought by multiple U.S. House of Representatives committees.
Lawyers for Trump did not immediately respond to requests for comment. Danny Frost, a spokesman for Vance, declined to comment. Mazars did not immediately respond to requests for comment but has said it would comply with its legal obligations.
'OVERREACH OF EXECUTIVE POWER'
In his 75-page decision, Marrero, who was appointed by Democratic President Bill Clinton, declined to assert jurisdiction over the Vance subpoena, saying Trump should have brought his case in a New York state court.
But the judge made clear that if the appeals court disagreed with that finding, Trump should lose, having failed to show that enforcing the subpoena would cause him irreparable harm or that the public interest supported an injunction.
"The expansive notion of constitutional immunity invoked here to shield the President from judicial process would constitute an overreach of executive power," Marrero wrote.
Marrero said there instead needed to be a balance between the president's need to perform his constitutional duties and the courts' legitimate interest in ensuring justice.
He said even President Richard Nixon had conceded during the Watergate scandal that he would be required to produce documents in response to a judicial subpoena.
Vance issued the subpoena four weeks after issuing another subpoena to the Trump Organization for records of hush money payments, including to two women prior to the 2016 election who said they had sexual relationships with Trump, which he denies.
The appeals court that will consider Trump's appeal in the Vance case heard oral arguments in the Deutsche Bank case on Aug. 23. It has yet to rule.
Trump is running for re-election. His current term ends on Jan. 20, 2021. (Reporting by Jonathan Stempel in New York; Additional reporting by Karen Freifeld and Brendan Pierson; Editing by Alison Williams and Steve Orlofsky)