By Sachin Ravikumar

LONDON (Reuters) - Brexit campaigner Nigel Farage's right-wing Reform UK is Britain's second most popular political party and sits just one percentage point behind the governing Labour Party, according to an opinion poll on Tuesday

Six months after Labour's landslide election victory, and with another vote not due until 2029, YouGov polling showed that if a general election were held tomorrow 26% of British voters would choose Labour and 25% would vote Reform UK. The Conservatives were on 22%.

The poll is YouGov's first since the July 4 election and showed Reform, which won 14% of the vote last summer, gaining support from the Conservatives and, to a lesser extent, Keir Starmer's Labour Party.

Farage's Reform has only five lawmakers in Britain's 650-seat parliament but after winning more than 4 million votes across the country is seen as a populist challenger to a British system historically dominated by Labour and the Conservatives.

Starmer's Labour, helped into power by voters' frustration with 14 years of Conservative government, has suffered a number of early setbacks including an outcry over ministers accepting freebies and the fallout of a badly received tax-raising budget.

The YouGov poll, which surveyed 2,279 people over the past two days, said only 54% of people who voted Labour in the last election would do so again.

Reform has the backing of Elon Musk, a close ally of U.S. President-elect Donald Trump, although the Tesla boss has withdrawn his support for Farage.

Elsewhere in Europe, Musk has also endorsed Germany's right-wing, anti-immigration AfD party ahead of national elections in February.

(Reporting by Sachin Ravikumar; editing by William James)