One of Prime Minister David Cameron’s parliamentary candidates said yesterday he had fallen out with the Conservatives and was switching his support to the anti-EU UK Independence Party (Ukip) before a May 7 election.

The move by Mike Whitehead, until last week the Conservative candidate for the seat of Hull West in northern England, is a morale boost for Ukip, whose support in some opinion polls has dipped after a series of racism and sexism scandals.

Ukip, which wants an immediate British withdrawal from the EU and sharply lower immigration, hailed the switch as a “hammer blow” to the Conservatives, who said they had sacked Whitehead last week over an internal party disagreement.

His defection is unlikely to cause a political upset, however, as the area is comfortably held by the opposition Labour Party, and neither the Conservatives nor Ukip are expected to win it.

Former Conservative candidate Mike Whitehead has switched his support to Ukip. Photo: PA Wire

Whitehead, who is also a sitting Conservative local councillor, said he had changed parties after becoming disenchanted with local Conservative politicians.

“I believe as a member of Ukip, I will be able to speak up for the residents,” he said in a statement. “The Conservative Party at national level has declined to get involved in what it sees as a remote internal squabble.”

Seeking to cast itself as a challenger to Cameron’s party in southern England and to Labour in northern England, Ukip said Whitehead’s defection proved its strategy was working.

“His move to Ukip just underlines that today, the real party of opposition to Labour in the North is Ukip. It is another hammer blow to Tory [Conservative] pretensions in the north of England,” said Nigel Farage, Ukip’s leader.

Labour said the move was “another huge blow for David Cameron’s authority.”

Though Britain’s first-past-the post electoral system means Ukip is unlikely to win more than a handful of seats, its popularity threatens to split the right-wing vote in particular, making it harder for Cameron to get re-elected.

Farage predicted on Sunday that several lawmakers from Cameron’s party would join Ukip’s ranks if the prime minister renewed a coalition with the pro-EU Liberal Democrats after next month’s election.

Two Conservative lawmakers defected to Ukip last year, causing Cameron political embarrassment.

Whitehead will not become Ukip’s parliamentary candidate for the Hull seat because the party already has one there, but he will seek re-election as a councillor for Ukip.