By Jack Queen

(Reuters) -A lawyer for one of former U.S. President Donald Trump’s co-defendants in his Georgia election interference case on Friday urged a judge to disqualify the lead prosecutor from the case, saying her undisclosed affair with a top deputy posed a conflict of interest.

The lawyer, John Merchant, said Fulton County District Attorney Fani Willis' affair with special prosecutor Nathan Wade, who receives a government salary, meant she had a personal financial interest in the case.

Merchant represents Michael Roman, one of 14 co-defendants in the criminal case.

"At the very least, she has created the appearance of unfairness for these defendants," Roman told Judge Scott McAffee.

Trump, the frontrunner for the 2024 Republican presidential nomination, and the others are accused of illegally pressuring Georgia officials to overturn his 2020 election loss in the state to President Joe Biden.

Trump has pleaded not guilty, along with his co-defendants.

A ruling in favor of Trump and his allies could further bog down a complex racketeering case that already faces a potentially long road to trial.

Disqualification of Willis would not necessarily end the case, as she would likely be replaced with a different district attorney.

But this would lead to significant delays, and a new prosecutor could narrow the charges or decide not to pursue the case.

The closing arguments before McAfee on Friday follow a series of evidentiary hearings where Willis conceded having an affair with Wade but accused a defense lawyer of lying about the timing and nature of the relationship.

The affair was first revealed in a January filing by a lawyer for Roman, who said it posed a conflict of interest and improperly enriched Wade.

Willis and Wade testified that the relationship did not begin until after Wade was hired, and prosecutors have said the relationship is irrelevant to the case because it did not harm the defendants.

Defense lawyers have accused the prosecutors of lying to the court, saying the relationship began before Wade was hired. In court papers filed last week, Trump's attorney cited location data from Wade’s cellphone suggesting he made numerous late-night visits to Willis’ home before she appointed him.

Trump is under indictment in three other state or federal criminal cases.

He is set to stand trial on March 25 in New York in a case accusing him of illegally covering up hush money payments to a porn star, which could be the only trial he faces before the November election.

Trump has also been charged in Washington over his efforts to reverse his 2020 election loss, but that case is paused until the U.S. Supreme Court decides whether he is immune from prosecution over actions he took while in office.

He is also under indictment in Florida over his handling of classified documents upon leaving office. The judge overseeing that case held a hearing on Friday on Trump's bid to move his May 20 trial date.

Trump has pleaded not guilty in all those cases and says they are part of a politically motivated plot to undermine his bid for office.

If he wins the presidency, Trump could use his presidential powers to end the Washington and Florida cases because they were brought in federal court.

He would not have the power to stop the Georgia case because it was brought in state court.

(Reporting by Jack Queen; Editing by Noeleen Walder, Daniel Wallis and Jonathan Oatis)