"I've never seen so much hand movement", Trump said.
Beto O'Rourke will seek the Democratic nomination to run for US president, a source close to his campaign and an El Paso TV station said Wednesday.
He already had planned a visit to Iowa this weekend.
An influential Iowa poll released last week showed O'Rourke as the first choice of just 5 percent of Democratic voters, behind four contenders, including former Vice President Joe Biden, who has not yet declared a bid, and U.S. Senator Bernie Sanders.
US Democrat Beto O'Rourke has said that he is running for president in 2020.
O'Rourke ran for a Senate seat representing the state of Texas in 2018, losing by less than three percentage points to Sen.
The trip will serve as the first test of whether O'Rourke can carry to the national political stage the pop-star appeal he showed in Texas a year ago, drawing enthusiastic crowds and $80 million in campaign donations.
O'Rourke, whose given name is Robert Francis, acquired his nickname while growing up in El Paso, Texas.
O'Rourke said he will hold a kick-off rally for his campaign on March 30 in El Paso, Texas.
His statement continued: "Beto O'Rourke failed to get anything done in Congress, and with extreme policies like government-run health care and tearing down border barriers, his 2020 bid won't be successful either".
"I'm not big on labels", O'Rourke told reporters in December when asked whether he could be considered a progressive.
O'Rourke is the 15th Democrat in the field and the second from Texas, and his opponents took notice.
King began by asking O'Rourke if he still feels Trump should be impeached. "I said, 'Is he insane or is that just the way he acts?'" He encouraged people to "study it".