By Jack Queen

NEW YORK (Reuters) -Eric Trump on Friday took the witness stand for a second day of questioning on the witness stand in a fraud trial that threatens to hobble the real-estate empire that vaulted his father Donald Trump to prominence.

The former U.S. president's second son has testified in a New York court that he knew nothing about the financial estimates of apartment towers, golf courses and other assets that a judge has already ruled were fraudulently inflated to win favorable terms from lenders and insurers.

But emails and other evidence introduced at trial show he was involved in decisions about how to value those properties. He has said he does not recall those discussions or was only involved with them peripherally while he oversaw other aspects of the sprawling business.

His testimony, due to begin at 10:00 a.m. ET (1400 GMT), was delayed as Trump lawyer Christopher Kise pressed Judge Arthur Engoron to lift a limited gag order that has prevented the former president from publicly criticizing court staff. Trump has already been fined $15,000 for violating that order twice.

Kise threatened to ask for a mistrial because Engoron's chief clerk allegedly engaged in political activity with Democratic officials. "We all need to take this very seriously, because the entire world is watching," he said.

Engoron questioned the accuracy of those allegations. "It's a shame we've descended to this level," he said.

Because Engoron has already ruled that Trump and his company fraudulently inflated asset values, the trial is largely about what penalty they should face.

New York Attorney General Letitia James is pressing for penalties of up to $250 million and a permanent ban on all three Trumps owning companies in their home state, among other restrictions.

Trump has denied wrongdoing and has accused James and Engoron of political bias in extensive comments online and in person.

Trump himself is due to testify on Monday, followed by his daughter Ivanka on Wednesday. She is not a defendant in the case.

The trial, which is expected to last until December, is one of several legal troubles confronting Trump as he campaigns to win back the White House.

He faces a total of 91 felony charges in four separate criminal cases, including two stemming from his attempts to overturn his 2020 election loss to Democrat Joe Biden.

Nevertheless, he holds a commanding lead over his rivals for the Republican presidential nomination.

The New York fraud trial has so far seen dramatic appearances by Trump's former lawyer and fixer Michael Cohen, who testified that Trump directed him to inflate asset values to make him appear more wealthy.

Trump's other son, Donald Jr., testified this week that he had little to do with those valuations when he and Eric controlled the company during their father's 2017-2021 stint in the White House.

(Reporting by Jack Queen; Writing by Andy Sullivan; Editing by Scott Malone, David Gregorio and Nick Zieminski)