How political violence has influenced US elections

As the dust settles following the attempted assassination of Donald Trump, a key question is how the failed bid may impact the upcoming White House election.

The US has a bloody history of political assassinations, with four presidents killed while in office. History also shows that such attempts can have very different effects at the ballot box.

Does surviving an assassination impact election performance?

Like Trump, Theodore Roosevelt was a former president attempting to return to the White House when he was shot on the campaign trail in Milwaukee in 1912. Folded papers and a metal spectacles case in his pocket absorbed some of the shot's impact, and he delivered his speech as planned – with the bullet lodged in his chest. Roosevelt, who was standing for his own Bull Moose Party, told his audience: "I don't know whether you fully understand that I have just been shot. But it takes more than that to kill a Bull Moose!"

The attempt on his life and his unflappable response "captured the imagination of the country", H.W. Brands, a historian at the University of Texas at Austin, wrote in a biography of the 26th president. But "as impressive as Roosevelt's performance that day had been, it did not propel him to victory", said The New York Times . The episode "was no political windfall" for Roosevelt, agreed Gzero Media , because although he secured more votes than sitting president William Howard Taft, they were both outflanked at the polls by the Democrat candidate, Woodrow Wilson .

In March 1981, Ronald Reagan was leaving a speech in Washington, D.C., and walking to his motorcade when he was shot by John Hinckley Jr. Reagan recovered physically from the shooting and so did his approval rating, which surged by eight points to nearly 70% in the aftermath of the incident.

His "grace under fire" helped him "solidify the support and affection of the American people", said CNN . The incident provided a "new baseline" of support that "propelled his legislative agenda forward".

Although "economic gloom" would pull his rating down by more than 40 points later in the year, said Gzero Media, Reagan had "more than three full years to bounce back" ahead of the 1984 election, and his "broad-based" landslide win, said CNN.

How have assassinations impacted politics?

The impact of actual assassinations "must remain a matter of speculation", said The Washington Post , because "we don't know what would have happened if the victims had lived". If Abraham Lincoln had survived in 1865 and continued as president, "would he have been able to bind the nation's wounds after the Civil War and guarantee civil rights for African Americans"?

Similarly, had John F. Kennedy lived, "would he have avoided a major US escalation in Vietnam" and "prevented the 1960s from turning into such a bloody and tumultuous decade"? The only answer historians can offer in these cases is a "not-very-satisfying 'perhaps'."

Will the Trump incident help or hurt his campaign?

Many commentators believe Saturday's shooting will "dramatically help" Trump's chances because it will "activate the MAGA base" amid "questions about whether Trump's base in particular was less mobilised than they were in years prior", said Vox . It could also win him "sympathy from", and help him "look tough to", a "general electorate".

"Outrage" at the shooting, alongside "relief at his close escape", will "provide him with the ideal stage on which to unite and galvanise his party", said the Daily Express . But Vox pointed out that the election is still nearly four months away and "many other events will consume the news between now and then", that "polling in this race has long been static", and that the identity of the shooter "may not fit easy political narratives".

Also, wrote Lester Munson on The Conversation , another "immediate consequence of the assassination attempt" will favour Trump's expected opponent: it will "turn the national conversation" temporarily away from Biden's much-criticised debate performance.