The FBI has warned of the possible for armed clashes linked to Tuesday’s US election in Portland, as the northwestern city that has become symbolic of the country’s stark divisions braces for unrest.

The liberal enclave in the state of Oregon is still reeling from a summer that saw mass anti-racism rallies inflamed by the arrival of federal officers and right-wing militias, including the so-called Proud Boys.

Tuesday’s fiercely polarized vote which could see President Donald Trump reelected, or defeated by his Democratic rival Joe Biden has spurred fears of more deadly street violence.

Downtown businesses were boarding up windows once again as protests are planned for either a Trump or a Biden win  or a state of limbo, with delays in the vote-counting expected nationwide due to a surge in mail-in voting during the pandemic.

“The thing that is the most concerning to me is the potential for armed clashes between opposing groups,” FBI Portland Special Agent Renn Cannon told AFP.

“That could escalate into a dangerous situation where — if tempers are heated — you could end up with an unfortunate or tragic act of violence,” he added, pointing to a deadly shooting of a far-right supporter in the city in August.

The 250-strong Portland office has committed additional resources to election crimes including voter suppression as well as fraud and foreign cyber threats, said Cannon.

Meanwhile Governor Kate Brown on Monday issued an executive order handing Portland policing to state forces — effectively overruling the city’s ban on tear gas — and putting the National Guard on standby.

“This is an election like no other in our lifetime,” she warned.