Donald Trump cannot block a prosecutor's subpoena for eight years of his tax returns, a federal judge ruled on Thursday, in the latest setback in the US president's longstanding effort to keep his finances under wraps.US District Judge Victor Marrero in Manhattan rejected Trump's claims that the grand jury subpoena from Manhattan District Attorney Cyrus Vance to the president's accounting firm Mazars USA was "wildly overbroad" and issued in bad faith. In a 103-page decision, Marrero also said letting Trump block the subpoena would amount to an "undue expansion" of presidential immunity.Trump quickly appealed the decision and filed an emergency motion to delay turning over his tax returns, saying enforcing the subpoena would cause him irreparable harm by disclosing his "private, confidential information."The litigation and grand jury secrecy rules make it unlikely Trump's financial records will become public before Nov. 3, when the president is seeking reelection.A spokesman for Vance declined to comment.Trump has long fought efforts by lawmakers and prosecutors to obtain those records, and by withholding his tax returns has departed from the decades-long practice of his predecessors.The case concerns an August 2019 subpoena related to Vance's criminal probe into Trump and his Trump Organization.In a court filing this month, Vance suggested the subpoena was related to "possibly extensive and protracted criminal conduct at the Trump Organization," including alleged insurance and bank fraud.Marrero rejected Republican Trump's accusations that the subpoena would let Vance, a Democrat, go on an improper "fishing expedition" into finances.He also accepted Vance's argument that letting Trump delay the subpoena's enforcement would effectively give the president "absolute temporary immunity" from the probe while in the White House.Unless enforcing the subpoena would affect his constitutional duties, "the President is entitled to claim no greater shield from judicial process than any other person," Marrero wrote. "Justice requires an end to this controversy."On July 9, the Supreme Court rejected Trump's earlier argument he was immune from state criminal probes while in the White House.Vance's probe began after reports that Trump's former lawyer Michael Cohen paid pornographic film actress Stormy Daniels $130,000 to buy her silence before the 2016 election about claimed sexual encounters with Trump, which he has denied.The case is Trump v Vance et al, US District Court, Southern District of New York, No. 19-08694.