A Missouri state lawmaker is being urged to resign Thursday after posting on Facebook that she hoped President Trump "is assassinated," according to reports.

Democratic Sen. Maria Chappelle-Nadal acknowledged that she made the now-deleted comment in a thread on her private Facebook page in response to her and another commenter's frustration with Trump's response in the aftermath of the Charlottesville violence, the St. Louis Post-Dispatch reported.

U.S. Sen. Claire McCaskill, D-Mo.; U.S. Rep. William Lacy Clay, D-Mo.; and other top Missouri Democrats have called on Chappelle-Nadal to step down.

"I am not resigning," Chappelle-Nadal told the St. Louis Post-Dispatch. "What I said was wrong, but I am not going to stop talking about what led to that, which is the frustration and anger that many people across America are feeling right now."

The U.S. Secret Service is investigating the case, according to the Associated Press.

Chappelle-Nadal, who has held elected office in Missouri since 2011, was a prominent critic of the Ferguson police shooting of Michael Brown in August 2014.