The FBI is investigating a confrontation on a Texas highway in which a caravan of President Donald Trump's supporters surrounded a Joe Biden campaign bus, an incident that has raised concerns about political intimidation just one day before the presidential election.

The confrontation occurred Friday, October 30, along Interstate 35 between San Antonio and Austin, where numerous pickup trucks and SUVs displaying Trump flags surrounded the Democratic campaign bus.

Videos circulating online show vehicles traveling dangerously close to the bus, with at least one minor collision involving vehicles accompanying the convoy.

Biden campaign officials say Trump supporters attempted to slow the bus and force it off the road. Campaign staff called 911, and several scheduled Texas campaign events were canceled because of safety concerns.

Neither Joe Biden nor his running mate, Kamala Harris, was aboard the bus. Campaign staff and Democratic congressional candidate Wendy Davis were among those traveling with it.

The FBI's San Antonio office confirmed Sunday that it was investigating the incident, although authorities have not announced any criminal charges.

Rather than condemn the confrontation, President Trump publicly celebrated his supporters.

On Saturday, Trump shared video of the incident on Twitter, declaring, "I LOVE TEXAS!"

On Sunday, he went further, defending the motorists and writing, "In my opinion, these patriots did nothing wrong."

Trump also suggested during a campaign rally that his supporters had been protecting the Biden campaign bus, a characterization disputed by the Biden campaign and contradicted by accounts of the confrontation.

The incident has intensified concerns about political intimidation and public safety as Americans prepare to vote Tuesday.

Democrats argue that the president's praise encourages aggressive behavior toward political opponents. Trump and his supporters maintain that the caravan was a demonstration of political enthusiasm.

With Election Day only hours away, federal investigators must now determine whether the actions of the motorists crossed the line from political expression into criminal conduct.

The controversy highlights the increasingly confrontational atmosphere surrounding an election already marked by extraordinary political divisions.