Former President Donald Trump called for unity and resilience Sunday after an attempt on his life added fresh uncertainty to an already tumultuous presidential campaign and raised sharp questions about how a gunman was able to open fire from a rooftop near a Pennsylvania campaign rally.

Setting aside stark political differences during a delicate stretch of the race, President Joe Biden used a prime-time address Sunday to condemn the violence and implore Americans that "we can`t, we must not go down` the road of political violence. `It`s time to cool it down and we have a responsibility to do that,` Biden said.