A day after Donald Trump survived an assassination bid, his 81-year-old Democrat rival and US President Joe Biden sought to calm a divided nation.

In a rare Oval Office address Sunday, he said it was time to lower the temperature of America’s hostile politics. “It’s time to cool it down,” Biden said in the televised speech.

He is urging Americans to “lower the temperature” and to resolve differences at the ballot box and not through bullets. “We cannot allow this violence to be normalised,” he said.

Investigators were still probing the motives of 20-year-old gunman Thomas Matthew Crooks, who was shot dead by snipers at the event in Butler, Pennsylvania, on Saturday after firing multiple shots with a legally-bought semi-automatic rifle.

Trump said on social media Sunday that Americans should not allow “evil to win,” adding it was “more important than ever that we stand United.”