“We must never allow political violence to take root in America,” Trump said Friday at the White House. “I am committed to doing everything in my power as president to stop it.”

Trump complained that he is often the target of hostility. “I get attacked also,” he said. “I get attacked all the time.” He added, “Who gets attacked more than me?”

The U.S. Justice Department said one person is now in custody in connection with the attempted bombings. The Associated Press identified the suspect as Cesar Sayoc of Aventura, Florida, citing law enforcement officials.

Television images from Plantation, Florida, showed a white van covered in pro-Trump and right-wing stickers being loaded onto a flatbed truck by law enforcement officers. The suspect is a man in his fifties who was arrested near an AutoZone store there and was being questioned by FBI agents, according to the Miami Herald.

Earlier in the morning, Trump had complained on Twitter that news coverage of the mail-bomb attempts was slowing Republican political momentum heading into the Nov. 6 congressional elections.

“Now this “Bomb” stuff happens and the momentum greatly slows – news not talking politics,” Trump said in a tweet Friday morning. “Very unfortunate, what is going on. Republicans, go out and vote!”

A dozen packages containing apparent explosive devices have been intercepted by authorities so far. The intended recipients have all been targets of conservative vitriol, with the most recent packages discovered addressed to New Jersey Democratic Senator Cory Booker and former Director of National Intelligence James Clapper. The first device was found Monday after being delivered to the home of billionaire financier George Soros.

Former President Barack Obama, former Democratic presidential nominee Hillary Clinton and former Vice President Joe Biden were also among the targets.