Rivals Joe Biden and Donald Trump urged Americans to show unity after an assassination attempt on the former United States president put the nation on edge in the run-up to the presidential election.
Biden addressed the nation from the Oval Office on Monday (AEST), a step only taken at times of grave crisis, after his .
"We can't allow this violence to be normalised. The political rhetoric in this country has gotten very heated. It's time to cool it down," Biden said.
"We all have a responsibility to do this."
Earlier in brief remarks from the White House, he said, "Unity is the most elusive goal of all, but nothing is more important than that right now."
The 81-year-old Democrat said he had a "short but good conversation" with Trump, his political nemesis whom he regularly brands as a threat to democracy.
Biden said the motives of the shooter, 20-year-old Thomas Matthew Crooks, remained unknown and urged people not to make assumptions about his "affiliations".
A day after being with blood streaked across his face, Trump made a similar call.
"In this moment, it is more important than ever that we stand United," Trump said in a statement on his Truth Social network, adding that Americans should not allow "Evil to win".
The tycoon added that it was "God alone who prevented the unthinkable from happening" and that he would "FEAR NOT".
Trump's wife Melania called the shooter a "monster".
"A monster who recognized my husband as an inhuman political machine attempted to ring out Donald's passion -- his laughter, ingenuity, love of music, and inspiration," Melania Trump said in a statement shared on social media platform X.
"When I watched that violent bullet strike my husband, Donald, I realized my life, and Barron's life, were on the brink of devastating change," she said, referencing the couple's 18-year-old son.
"I am grateful to the brave secret service agents and law enforcement officials who risked their own lives to protect my husband," Melania Trump said.
Security in question in Trump attack aftermath
Secret Service snipers killed Crooks after he fired multiple shots at the rally from a nearby rooftop. A bystander was killed and two spectators critically injured in the worst act of US political violence in decades.
Biden said he had ordered a full review of security at the rally, as well as at this week's Republican National Convention in Milwaukee where Trump will be crowned the party's presidential nominee.
Biden also praised the victim, identified as Corey Comperatore, saying the victim "was protecting his family from the bullets".
Questions are swirling about the motive of shooter Crooks, whose body was seen in television images on a low roof of a building, near a weapon understood to have been an AR-15-style semiautomatic rifle.
Investigators had found explosive material in his car parked near the scene, US media said, while the Federal Bureau of Investigation also searched his house.
The shooter, reportedly a registered Republican, was believed to be working alone.
His father Matthew Crooks told CNN that he was trying to establish "what the hell is going on".
The shocking incident also drew criticism of security at the rally, particularly about how a presidential candidate could be targeted by a gunman around 150 meters away despite a huge Secret Service detail.
US Secret Service spokesperson Anthony Guglielmi rejected "absolutely false" claims that it had refused additional protection for Trump ahead of the rally.
Shock waves across the US and the world
The attempt on Trump's life sent shock waves around the world, but the effects on a tight US presidential race in a deeply divided country are uncertain.
Trump's family has already been promoting images of the president raising a defiant fist to the crowd after the shooting.
Trump said that he was "shot with a bullet that pierced the upper part of my right ear" and heard a "whizzing sound."
His narrow escape has sparked conspiracy theories and finger-pointing by Republicans. Possible Trump vice-presidential pick JD Vance claimed Biden's campaign "rhetoric" had "led directly" to the attack.
US politics have become increasingly hostile, with Trump building his image around inflammatory verbal assaults, and many Democrats expressing fury and disgust at Trump's rise.
over the assassination attempt, with UN chief António Guterres saying he condemned it "unequivocally".
The United States has a history of political violence. Former president John F Kennedy was assassinated in 1963 while former president Ronald Reagan was shot but survived an assassination attempt in 1981.
