A Democratic senator mocked one of President Trump's judicial nominees on Thursday, posting video of the nominee struggling to provide answers to a GOP senator's line of questioning.

Sen. Sheldon Whitehouse (D-R.I.) posted video of Matthew Spencer Petersen, a commissioner on the Federal Election Commission, facing questions during a hearing Wednesday on his nomination to become a district judge on the U.S. District Court for the District of Columbia.

Whitehouse touted the video as a "MUST WATCH," noting that the nominee was unable to answer "basic questions of law" after being asked by Sen. John Kennedy (R-La.) about legal procedure.

"Hoo-boy," Whitehouse tweeted.

After asking Petersen and four other nominees in the video whether they had ever "tried a case to verdict," Kennedy narrowed his questioning to Petersen, who admitted he had not.

"Do you know what a motion in limine is?" Kennedy asked.

"I would probably not be able to give you a good definition," Petersen responded.

"Do you know what the Younger abstention doctrine is?" Kennedy continued.

"I've heard of it, but again," Petersen responded, trailing off.

"How about the Pullman abstention doctrine?" Kennedy added. Again, Petersen was unable to respond, shaking his head.

Petersen defended his inability to answer the questions in a brief statement, telling Kennedy that he is aware that his path to the nomination for a district judge was unorthodox.

"I haven't had to do a deep dive ... and I understand, and I appreciate this line of questioning, I understand the challenge that would be ahead of me if I were fortunate enough to be named a district court judge," he said.

"I understand that the path many successful district court judges has been a different one than I have taken," Petersen continued, adding that he believed that he was still qualified.

The White House announced this week it would withdraw two controversial judicial nominees opposed by Sen. Chuck Grassley (R-Iowa), who chairs the Senate Judiciary Committee. Those nominees were under fire for controversial statements made in the past, and one had also practiced law for less than three years.