Labour and the Conservatives said the result of the Clacton by-election would not draw a line under the saga surrounding donations received by Nigel Farage.
Polls closed at 10pm in the election which has been shunned by the other major political parties, with Mr Farage hoping to retain his seat.
A record 34 candidates are standing. Satirical candidate Count Binface appears to Mr Farage’s main challenger.
Labour’s chair Bridget Phillipson said Mr Farage “can’t run from the truth forever”.
Meanwhile, a spokesperson for the Conservative Party said the “stunt” of calling the by-election would not draw a line under it.
The Reform UK leader quit as an MP to trigger the by-election in protest at media and parliamentary scrutiny of donations from his backers.
Mr Farage said it was a chance to “stick two fingers up to the establishment”.
Ms Phillipson said: “Nigel Farage spent 38 days fighting a bin in his most desperate attempt yet to deflect attention from the sleaze and scandals engulfing him and his Party.
“Farage may succeed in his run-off against a bin, but he can’t run from the truth forever. The list of unanswered questions about the £5 million gift he hid from the public, his support from a convicted fraudster, and the mountain of other scandals he and Reform are facing isn’t going away.
“In fact, it’s getting longer by the day.
“It’s time to stop the excuses and desperate distractions and finally come clean with the public. If Farage has nothing to hide, he surely would have done so by now.”
A Conservative Party Spokesman said: “Nigel Farage called this fake by-election in a desperate attempt to draw a line under the questions surrounding his fishy £5 million donation.
“Whatever the outcome on Friday, this stunt has not done that.”
The result is likely to be announced in the early hours of Friday morning. Initial returns show that turnout is down about 15% on the election in July 2024.
Mr Farage wanted it to be a “people versus the establishment” showdown but, rather than Labour and Tory rivals, he is facing opponents including Count Binface, actor-turned-politician Laurence Fox, three from the Official Monster Raving Loony Party and an array of independents.
The contest is estimated to have cost taxpayers about £250,000.
Photographers and TV cameras covering the count have been advised by officials they will need a wide-angle lens to fit all the candidates into a single shot.
Before quitting Westminster, Mr Farage was being investigated by the parliamentary standards commissioner Daniel Greenberg over a £5 million gift from cryptocurrency tycoon Christopher Harborne, which he received before taking his seat in the Commons.
Under Commons rules, new MPs are required to register any gifts worth more than £300 they received in the previous 12 months, except where the gift “could not be reasonably thought by others” to relate to their political activities.
That investigation was paused when Mr Farage resigned his seat but will resume if he wins the by-election – as bookmakers have made him the firm favourite to do.
Mr Farage could also face an investigation over support provided by George Cottrell, a long-term ally.
Mr Cottrell reportedly recruited and paid three staff to work on Mr Farage’s social media before the general election, and has continued to allow him to use a five-storey, Georgian property he rented near Buckingham Palace.
The main Westminster parties refused to take part in this contest but could stand if the outcome of the standards investigation into Mr Farage results in another by-election.
If he is found to have broken the rules and a suspension of more than 10 days is imposed, it could trigger a recall petition and the prospect of Mr Farage losing his seat, forcing a second contest.
In the 2024 general election, Mr Farage won Clacton with 46.2% of the vote and a majority of 8,405 over his Conservative rival.
Labour Party chairwoman Bridget Phillipson said: “Nigel Farage spent 38 days fighting a bin in his most desperate attempt yet to deflect attention from the sleaze and scandals engulfing him and his party.
“Farage may succeed in his run-off against a bin, but he can’t run from the truth forever. The list of unanswered questions about the £5 million gift he hid from the public, his support from a convicted fraudster and the mountain of other scandals he and Reform are facing isn’t going away. In fact, it’s getting longer by the day.
“It’s time to stop the excuses and desperate distractions and finally come clean with the public. If Farage has nothing to hide, he surely would have done so by now.”
A Conservative Party spokesman said: “Nigel Farage called this fake by-election in a desperate attempt to draw a line under the questions surrounding his fishy £5 million donation. Whatever the outcome on Friday, this stunt has not done that.”
The candidates for the Clacton constituency are:
– Joseph 77 (Independent)
– Adham Alkhatip (The Forward Party)
– Count Binface (Count Binface Party)
– Nick The Incredible Flying Brick (The Official Monster Raving Loony Party)
– Tony Cane (Independent)
– Woke Trump Carrzee (Independent)
– William Stuart James Clouston (Social Democratic Party)
– Rees Cowne (Independent)
– Glenn Charles Cummings (Independent)
– Martin Davies (Freedom Alliance – Real People, Real Alternative!)
– Andy Erlam (Independent)
– Nigel Farage (Reform UK)
– Attieh Fard (Independent)
– Laurence Fox (The Reclaim Party)
– Tony Francis (Independent)
– Robin Green (Independent)
– Abi Hookway (Independent)
– Howling Laud Hope (The Official Monster Raving Loony Party)
– Stephen Richard Ingram (Independent)
– Amy Morris (Independent)
– Derrick Norbert Morris (Independent)
– Michael Noel O’Keeffe (Independent)
– Martyn OBrien (Independent)
– Nick Pelas (Independent)
– Ketankumar Pipaliya (UK VOICE safer and stronger UK)
– Daniel Pocock (Independent)
– James Ransley (Consensus Party Candidate)
– Gerry Smith (Independent)
– Kai Stephens (British Democrats)
– John Stevens (Rejoin EU)
– Baron Von Thunderclap (The Official Monster Raving Loony Party)
– Pamela Walford (Independent)
– Marcus White (Everyone is God Party)
– Marc Wilkinson (Independent)
