WASHINGTON — Democratic Sen. Elissa Slotkin of Michigan is refusing to voluntarily comply with a Justice Department investigation into a video she organized urging U.S. military members to resist “illegal orders” — escalating a dispute that President Donald Trump has publicly pushed.

In letters first obtained by AP , Slotkin’s lawyer informed U.S. Attorney for the District of Columbia Jeanine Pirro that the senator would not agree to a voluntary interview about the video. Slotkin’s legal team also requested that Pirro preserve all documents related to the matter for “anticipated litigation.”

Slotkin’s lawyer separately wrote to Attorney General Pam Bondi, declining to sit for an FBI interview about the video and urging her to immediately terminate any inquiry.

The refusal marks a potential turning point in the standoff, shifting the burden onto the Justice Department to decide whether it will escalate an investigation into sitting members of Congress or retreat from an inquiry now being openly challenged.

“I did this to go on offense,” Slotkin said in an interview Wednesday. “And to put them in a position where they’re tap dancing. To put them in a position where they have to own their choices of using a U.S. attorney’s office to come after a senator.”

Last November, Slotkin joined five other Democratic lawmakers — all of whom previously served in the military or at intelligence agencies — in posting a 90-second video urging U.S. service members to follow established military protocols and reject orders they believe to be unlawful.

The lawmakers said Trump’s Republican administration was “pitting our uniformed military and intelligence community professionals against American citizens” and called on troops to “stand up for our laws.”

The video sparked a firestorm in Republican circles and soon drew the attention of Trump, who accused the lawmakers of sedition and said their actions were “punishable by death.” The Pentagon later announced it had opened an investigation into Arizona Sen. Mark Kelly, a former Navy pilot who appeared in the video. The FBI then contacted the lawmakers seeking interviews, signaling a broader Justice Department inquiry.

Slotkin said multiple legal advisers initially urged caution. “Maybe if you keep quiet, this will all go away over Christmas,” Slotkin said she was told.