WASHINGTON — President Donald Trump said Thursday that he was struck by Democratic presidential candidate Beto O'Rourke's gesticulations during the former Texas congressman's first day on the campaign trail.

"Well, I think he's got a lot of hand movement. I've never seen so much hand movement. I said, 'Is he crazy or is that just the way he acts?'" Trump said at the White House. "I watched him a little while this morning, during I assume it was some kind of a news conference, and I’ve actually never seen anything quite like it."

O'Rourke, who served three terms in the House before losing to Trump-backed Republican incumbent Ted Cruz in a Senate race last November, launched his campaign with a video sent to supporters and spoke with voters in Iowa Thursday.

He excited many Democratic activists across the country with a campaign that turned ruby-red Texas into a competitive battleground in 2018, with Cruz defeating him by just 2.5 percentage points. But he entered a crowded field for his party's presidential nomination and the right to take on Trump in 2020.

Trump dodged a question about whether he thought O'Rourke or former Vice President Joe Biden, who has not yet announced his intentions, would make for a tougher opponent.

"I just say whoever it is, I’ll take him on," Trump said, repeating himself but adding "or her" to reflect the possibility that the Democratic nominee could be one of several women who are running.

While Trump likes to give his rivals derisive nicknames — he calls Sen. Elizabeth Warren, D-Mass., "Pocahontas" to remind voters that she has claimed Native American heritage — the White House is instead referring to O'Rourke as "Robert Francis," which is his given name. "Beto" is a nickname he has used since childhood.