President Donald Trump mocked Beto O'Rourke for his competing rally in El Paso, Texas, Monday, saying that he had a "tiny little line" of supporters.

Many consider the rally by the failed Democratic candidate for the U.S. Senate to be a trial balloon for a possible presidential campaign in 2020. Although O'Rourke was unable to unseat Sen. Ted Cruz (R-Texas), he was able to get much closer than many expected.

"We have a line that's very long already," Trump said to reporters ahead of his rally. "You've seen what's going on. I understand our competitor's got a line too, but it's a tiny little line."

The president is expected to make the argument for his border wall at the rally in the border town he's pointed to as an example of the success of border enforcement.

Who has more supporters in El Paso?

Although supporters of O'Rourke would love to see him have a better showing in his hometown, WFAA-TV reporter Jason Whitely said that only a couple of thousand of people showed up.

Thirty minutes after he posted photos of the O'Rourke crowd, the president's 2020 campaign manager Brad Parscale tweeted a photo of the thousands waiting for Trump to appear at his rally.

Parscale later claimed that O'Rourke only had 900 supporters, and that the president had tens of thousands at the rally and outside.

CNN's Jeff Zeleny reported that he believed O'Rourke's crowd to be "a few thousand."

Here's the latest on the Trump O'Rourke rally feud: