US President Donald Trump speaks to the members of the media before leaving the White House in Washington, Friday, Oct. 26, 2018, to attend a campaign rally in Charlotte, N.C. (AP Photo)

US President Donald Trump said Friday that he knows the pipe bomb suspect was one of his supporters, but said he bears "no blame" for the suspect's actions.

"There is no blame. There's no anything," Trump told reporters at the White House before leaving for a political rally in North Carolina.

"If you look at what happened to Steve Scalise, that was a supporter of a different party," he said, recalling the 2017 shooting at a Republican baseball practice that left several wounded, including the congressman from Louisiana.

Asked if he planned to tone down the partisan rhetoric at rallies, which his critics contend has deepened political divisions in the country, Trump replied: "I think I've been toned down. You know, I could really tone it up."

With a suspect in custody, Trump pledged to prosecute those responsible for the pipe bomb scare "to the fullest extent of the law." He called for national unity just hours after complaining that all the focus on "this 'Bomb' stuff" was distracting from the midterm elections.

Trump, in his first remarks since Cesar Sayoc was apprehended in Florida, declared that "we must never allow political violence take root in America." At least a dozen explosives have been sent in recent days to political opponents of the president, gripping the nation and escalating political tensions just days ahead of the midterms.