(Reuters) -Federal Reserve Governor Lisa Cook, fighting U.S. President Donald Trump's unprecedented effort to fire her from the central bank, has tapped a prominent Washington lawyer who launched a new firm this year to represent officials targeted by the Republican president.

Abbe Lowell, whose clientele includes Hunter Biden and New York Attorney General Letitia James, said on Tuesday that he and Cook will file a lawsuit after Trump announced he was firing Cook over mortgage fraud allegations.

Lowell in a statement said Trump lacks authority to remove Cook from the politically independent Fed. "His attempt to fire her, based solely on a referral letter, lacks any factual or legal basis," he said.

Lowell was a partner at major U.S. law firms before announcing in May he was opening his own firm to represent government officials under fire by the Trump administration.

Cook, appointed by Democratic President Joe Biden in 2022, is the first African-American woman to serve on the Federal Reserve's governing body.

Trump in a letter announcing his move to fire her on Monday said he had "sufficient cause to remove you from your position" because in 2021 Cook had indicated on documents for separate mortgage loans on properties in Michigan and Georgia that both were a primary residence where she intended to live.

Cook has denied wrongdoing and has not been charged.

Lowell represented Biden's son Hunter against criminal gun and tax charges before he was pardoned in December. He has also represented former Democratic U.S. Senator Bob Menendez, failed Democratic U.S. presidential candidate John Edwards, Trump's ex-wife Ivanka Trump and Trump's son-in-law Jared Kushner.

New York's attorney general James hired Lowell after the Trump administration referred her to the Justice Department for allegedly falsifying real estate records. James has denied the allegations.

Lowell is also a lead attorney in a lawsuit filed in July accusing the Justice Department of illegally firing three former government employees, including a lawyer who prosecuted people involved in the Jan. 6, 2021, attack on the U.S. Capitol.

His new firm employs two former lawyers at Skadden Arps who quit over its response to Trump's executive orders targeting the legal profession. Skadden is one of nine firms that cut deals with the administration to avoid Trump's crackdown on firms he accused of "weaponizing" the legal system, while four other firms successfully sued.