Voters in suburban New York were choosing a congressman to replace scandal-plagued George Santos on Tuesday, with Democrats pouring cash into TV ads to try to take his seat from the Republicans in an election year.
Democrat Tom Suozzi is facing off against Republican Mazi Pilip, with polls open despite heavy snow.
The winner of the special election will serve out the remaining 11 months of ousted Santos' term in the House of Representatives, where a Democrat victory would chip away at the Republicans' narrow majority.
Aggressive attack ads were run in the campaign, with Republicans seeking to paint Suozzi as soft on illegal immigration, while Democrats have sought to frame Pilip as an anti-abortionist.
Migration and abortion are central political issues as the United States limbers up for the presidential election set to pit President Joe Biden against Donald Trump in a re-run of the 2020 contest.
One attack ad shows archive footage of Suozzi apparently boasting that he fought to keep immigration enforcement officers out of Nassau County when he was the area's top elected official.
Anti-Pilip ads have suggested she would seek a nationwide ban on terminations.
Deep snow in New York's third Congressional district, which includes eastern city suburbs and Long Island's wealthy North shore, threatened to complicate voting as authorities warned against driving.
Suozzi's campaign responded by offering a dial-a-ride service for voters.
Santos became only the third person to be ejected as a US lawmaker since the Civil War, in a rebuke previously reserved for traitors and convicted criminals.
He had won a House seat in 2022, helping the Republicans to a tiny majority, but it quickly emerged that his backstory was largely a fabrication.
"You, sir, are a crook," said one of several members of his own party to denounce him on the House floor last year over colorful fraud allegations.
Santos, who has denied criminal charges, allegedly used donor money for Botox treatments and the OnlyFans porn website, as well as luxury Italian goods and vacations, according to the committee that probed his conduct.
While the constituency backed Biden in 2020, Republicans took several seats in the area in 2022 and have an effective local operation to get out the vote.