US President Joe Biden called on Americans to "lower the temperature" Sunday following the attempted assassination of his political rival Donald Trump.

"My fellow Americans, I want to speak to you tonight about the need for us to lower the temperature in our politics," Biden said in an address to the nation from the Oval Office. "Politics must never be a literal battlefield, God forbid a killing field."

"All of us now face the time of testing as the election approaches. The higher the stakes, the more fervent the passions become," he added. "No matter how strong, our convictions must never descend into violence... It's time to cool it down."