LONDON British Prime Minister Rishi Sunak will on Monday say only his Conservatives can counter a Labour-led government and that a vote for Nigel Farage's right-wing Reform UK would hamper any chance of his party forming a strong opposition.

Appearing to all but concede defeat before Thursday's election, Sunak will appeal to those voters on the political right who are considering voting for Farage's party in protest at his Conservative government.

The Conservatives look set to be kicked out of office after 14 turbulent years, marked by Britain's vote to leave the European Union in 2016 and the cost of living crisis that followed the Covid-19 pandemic and Russia's invasion of Ukraine.

Opinion polls have consistently given Keir Starmer's centre-left Labour Party an around 20 point lead, with support for Reform potentially splitting the centre-right vote and the centrist Liberal Democrats further draining Conservative support.

Sunak will say at a rally that Reform "just won't win enough seats to oppose Labour", saying the party had previously said it would be good to get a handful of Reform members of parliament.

"Just imagine that: Hundreds and hundreds of Labour MPs opposed by just 'one, two, three, four, five elected MPs'," Sunak will say, according to extracts of his speech.

"A Labour government would be bad for our country, and an unchecked Labour government would be a disaster from which it would take decades to recover."

Farage is one of Britain's most recognisable and divisive politicians. He has spent decades railing against the establishment and the European Union, and has in recent years campaigned for Donald Trump in the United States.

He entered the election in early June - his eighth attempt at winning a seat in the Westminster parliament - vowing to supplant the Conservatives as the main party of the right.

Polls appear to show that Reform's support peaked in the second half of June, shortly before Farage said the West provoked Russia's invasion of Ukraine. Some of his candidates and supporters have been dropped for racist or inappropriate remarks.

While Britain's electoral system means Reform may win millions of votes, the party is unlikely to win more than a handful of parliamentary seats. But that could be enough to split the right in many areas and hand victory to Labour.

Reform said on Monday its membership had doubled from 30,000 to 60,000 in a month, and that donations would help it fund an advertising campaign through the last week.

"It is humbling but also very telling that they are prepared to back their faith in Reform UK with hard-earned cash and I thank each and every one of them," Farage said in a statement.

Britain will likely elect a centre-left government as much of Europe swings right, including in France where Marine Le Pen's far-right National Rally won the first round of a parliamentary election on Sunday.

With polls showing many voters are undecided, Sunak will make a final appeal for people to limit Labour's power if it gets into government, saying: "We Conservatives will stand up for you and make sure your voice is heard, your values represented."

  - Reuters