Australian election watchers have been glued to their screens as Donald Trump claimed a remarkable return to the US presidency.

Just after 6pm AEDT on Wednesday, the outspoken Republican took to the stage to declare victory over Democratic opponent Kamala Harris.

Expats and political junkies had earlier watched on from the other side of the world as Americans cast their votes.

As the first polls closed on the US east coast, the crowd started to swell inside one Sydney watering hole in the late morning.

Maggie Donahue was an earlier arrival and scored a prime spot near a screen tuned to CNN.

Ms Donahue, who worked for the US government over six years spanning the Trump and Biden administrations, was cautiously hopeful of a Harris win.

"I was in a federal government building the day of January 6, 2021," she said, referring to the date a mob of Trump supporters stormed the US Capitol.

Democrat supporter Amy Saha said she was hopeful Kamala Harris would be elected. (Bianca De Marchi/AAP PHOTOS)

Amy Saha, a committee member of Democrats Abroad Australia, said she was also quietly "but absolutely optimistic".

Ms Saha wore a star-spangled top hat and attendees could take photos with a cardboard cut-out of Ms Harris at the Sydney event.

The pub served American-brand beers and food including bagels and Buffalo wings, while the steak carried a side of "Freedom fries".

Sharing a bucket of Coors in the back of the Sydney pub, Ben, who declined to give his last name, said the beers were "alright" but not the main point of attending.

"We're coming here to support our president ... it's a Trump victory, unless they rig it of course," he said.

Sitting across the table, Dean Thorby said the Republican candidate's vacillation on abortion might cost him votes from women, but he still expected a Trump victory.

"Just because he's way more populist, she's way more of a drone," he said.

Political junkies attended US election watch parties as the votes rolled in. (James Ross/AAP PHOTOS)

In Melbourne, more than 50 people attended an American Chamber of Commerce watch party.

The room at the Hawthorn Hotel was abuzz at 3pm as the election picture started to become clearer.

Melbourne resident Gavin, who has US business interests and did not wish to have his surname published, said results in the swing states were breaking Trump's way.

"I haven't seen Harris flip a state," the septuagenarian said with beer in hand.

Brisbane-based management consultant Emilia Gallo, who has worked for American companies in Asia and was firmly in the Harris camp, remarked on the ramifications of either outcome.

"It's either going to make us go 'oh my God, what the hell is going on' or 'thank God, they've came to their senses'," she said.

By Jack Gramenz and Callum Godde in Sydney