EL PASO, Texas ― Thousands are expected to turn out Monday night to protest President Donald Trump’s demands for a border wall and his insistence that this overwhelmingly Democratic city is the best place to make the case for it.

The protests set up a clash between Trump and a potential opponent in 2020: Democrat Beto O’Rourke, a born-and-raised El Pasoan who is speaking at the protest set up as counter-programming to the president’s Monday evening rally in the city.

O’Rourke insisted Monday that his appearance at the protest wasn’t a personal challenge to Trump and instead was meant to be in support of the more than 50 community groups that organized the march.

“I think he’s here in an effort to use this community as a prop to make his case for the border wall,” O’Rourke told reporters on a call.

The competing protest clearly got the president’s attention.

“We have a line that is very long already,” Trump said before leaving Washington for El Paso. “I mean, you see what’s going on. And I understand our competitor has got a line too, but it’s a tiny, little line. Of course, they’ll make it sound like they had more people than we do. That’s not going to happen.”