A senior Conservative party member in Ealing Southall has defected to the Lib Dems over the selection of their new parliamentary candidate.
Last week the Conservatives chose businessman Tony Lit to fight the Ealing Southall by-election, triggered by the death of Labour MP Piara Khabra.
Today the deputy chair of Ealing Southall Conservatives announced his defection to the Lib Dems, claiming Mr Lit was foisted on the local party by Tory spin doctors.
Brij Mohan Gupta, who is also vice chair of Southall Green and Southall Broadway Conservative ward parties, announced he will instead campaign for the Lib Dem candidate Nigel Bakhair.
Chair of the Liberal Democrats campaign committee, Edward Davey welcomed his decision.
He said: "Senior Conservative party members across Ealing Southall are extremely unhappy with the way David Cameron runs the Tory Party.
"People want their political leaders to have clear principles and policies, but under Mr Cameron even once loyal party members say the Conservatives seem prepared to say anything to win votes."
The defection follows Quentin Davies MP's defection across the floor to Labour after launching a public attack on David Cameron's modernisation of the party.
Mr Gupta said he completely agreed with Mr Davies and said Mr Cameron had turned the Conservatives into a party of style over substance.
He said: "This by-election reflects Mr Cameron's contempt for local Conservative members.
"His spin doctors ignored our wishes and forced the branch to accept someone whose commitment to the party is less than a week old. Almost all local Conservative party members feel like I do."
However, the local Conservative party defended the choice of Mr Lit, saying he had enjoyed links with the local area for more than a decade.
Anita Kapoor, chairman of Ealing Southall Conservatives, said she was disappointed by Mr Gupta's decision but knew the party had a fantastic candidate in Mr Lit.
A party spokesman played down Mr Gupta's defection to the Lib Dems and implied it was motivated by his failure to be selected as the local Tory candidate.
He told politics.co.uk: "Mr Gupta was kind enough to put forward his CV for consideration to become MP for Ealing Southall. Obviously only one person can be selected from a large list.
It's a shame Mr Gupta, having not been selected, then decided to leave the party."
Meanwhile, Westminster rumours suggest another Tory MP will cross the floor and follow Mr Davies, who announced his defection to Labour on the eve of Gordon Brown's premiership.
The promotion of Shaun Woodward to Northern Ireland secretary is being interpreted as a signal from Mr Brown that he is willing to reward Tory turncoats.
While party politicking gains force in London ahead of the July 19 by-election, the major parties have also begun to announce their candidates for Tony Blair's Sedgefield constituency.
The Lib Dems and Labour are meeting to debate their candidates today. The Conservatives have selected Graham Robb while Ukip are fielding Toby Horton, who stood against Mr Blair as a Tory candidate in 1983.