In the opening moments of a Friday rally, Republican presidential nominee Donald Trump warned supporters of what could be if Hillary Clinton wins in November and assumes the presidency, arguing that she will destroy America from the White House.

Trump told supporters in Des Moines, Iowa, that Clinton will engage in the "destruction of this country from within" if she wins in three months

"If Hillary Clinton becomes president, you will have terrorism, you will have problems," Trump told the crowd. "You will have, really in my opinion, the destruction of this country from within."

Soon after, Trump continued to take aim at Clinton, arguing that she is "pretty close to unhinged" before going on to promote a recent book by Gary Byrne, a former Secret Service agent, in which he called her leadership style "volcanic and impulsive".

"She's really pretty close to unhinged," Trump said. "She's like an unbalanced person. In the words of a Secret Service agent … she's simply, this is a quote, 'she simply lacks the integrity and temperament to serve in the office.'"

Earlier in the week, Trump upped his attacks against the former secretary of state, telling supporters in Harrisburg, Pa., that she is "the devil," adding that Sen. Bernie Sanders made a "deal with the devil" by endorsing her ahead of and during the Democratic National Convention.