Democrat Beto O’Rourke headlined a protest Monday night across the street from an arena in which President Donald Trump promoted his long-promised border wall between the United States and Mexico.

The former congressman, who is considering a presidential run in 2020, says, “We are making a stand for the truth.” He says, “Walls do not save lives, walls end lives,” citing the danger to asylum seekers who are rejected by the U.S.

While attendees chanted “Beto!” during breaks in O’Rourke’s speech, President Donald Trump boasted about the size of the crowd attending his rally in El Paso, Texas, versus that for former Democratic Rep. Beto O’Rourke.

Trump said O’Rourke had little going for himself and noted that he lost a Senate race to Republican Ted Cruz. The president did credit him for having a “great first name.”

The ex-congressman is still deciding on a presidential run. But treating the political world to 2020’s first dueling rallies may indicate O’Rourke is ready to join the race.

The Associated Press contributed to this story.