Former White House chief of staff Mark Meadows will not testify in Congress’s probe of the Jan. 6 “Stop the Steal” rally amid a burgeoning legal battle over executive privilege, according to Meadows’s lawyer.

The Jan. 6 committee was formed in June in a mostly party-line vote, as all but two Republicans—Reps. Adam Kinzinger (R‑Ill.) and Liz Cheney (R‑Wyo.)—voted against forming the commission. The committee is led almost exclusively by Democrats, with Kinzinger and Cheney the only Republicans sitting on the panel.

For weeks, tension has been building between the mostly Democratic panel and former President Donald Trump.

The commission has subpoenaed documents and testimony from former Trump officials regarding the Jan. 6 rally. Trump has maintained that he and former administration officials are exempt from providing this testimony due to executive privilege, long a mainstay in U.S. presidential politics.