“Well I think he has got a lot of hand movements,” the president said during a White House meeting with Irish Taoiseach Leo Varadkar. “I've never seen so much hand movement.”
He added, “Is he crazy or is that just the way he acts?”
The president declined to comment on whether Mr O’Rourke was a stronger opponent than former Vice President Joe Biden, who has not yet launched a bid for the White House.
Mr Trump also commented on Brexit, claiming things had become difficult with the European Union, and the Senate vote on Thursday to condemn his national emergency declaration that would allow him to circumvent Congress and pull federal funds to build his long-promised US-Mexico border wall.
While the president has regularly attacked lawmakers entering the 2020 race, Mr O’Rourke called for unity and a “positive campaign” during an announcement video on Thursday morning.
“This is going to be a positive campaign that seeks to bring out the very best from every single one of us, that seeks to unite a very divided country,” he said alongside his wife, Amy.
The southern Democrat added, “We saw the power of this in Texas,” referring to his long shot 2018 senatorial campaign in the deeply red Lone Star state.
Mr O’Rourke’s entry is already reverberating around the crowded field of Democratic presidential hopefuls. Kamala Harris singled him out by name in a Thursday email to supporters, noting that a “record number of women and people of color” are running and adding she was looking forward to “substantive debates” with candidates including “the newest to join the race today, Beto O’Rourke.”
He had never before visited Iowa, which kicks off presidential voting, but said during his first stop at a coffee shop there on Thursday, “I could care less about your party persuasion, your religion, anything other than the fact that, right now, we are all Americans.”
His comments were carried live on several cable TV networks, the kind of exposure other 2020 Democrats don’t often get.
Mr O’Rourke has promised to travel the country listening to voters, then will return to El Paso, on the border with Ciudad Juarez, Mexico, on March 30 for an official campaign kickoff.
Additional reporting by AP