Nigel Farage has hinted that more MPs could follow Douglas Carswell by defecting to his party before the election.
The Ukip leader said politicians among the Conservative and Labour ranks "feel strongly" on the issues the party stands for.
"I don't think anybody will say that Douglas Carswell coming to Ukip is a one-off.
"There are many other people out there that are making up that calculation now," he added.
Nigel Farage, the Ukip leader, and the party's new candidate for Clacton have been campaigning on the streets of the seaside town this morning.
Douglas Carswell will contest the seat for the eurosceptic party after defecting from the Conservatives yesterday, triggering a by-election for the constituency.
Tory defector Douglas Carswell said "I stab people in the front, not the back" as he defended his decision to quit the party.Read the full story ›
Ukip's general election candidate for Clacton has vowed to fight Douglas Carswell for the party's nomination in the upcoming by-election.
Roger Lord said he would "absolutely" fight for the nomination. "I have been assured I will get a fair hearing," he told Radio 4's Today programme.
Asked whether he would step aside to make way for Mr Carswell, Mr Lord replied, "We are not a party that stands down. We don't bend, we don't break. We fight."
Mr Lord also accused Mr Carswell of jumping ship from the Conservatives because the water was "around his ankles".
Nigel Farage has reiterated more Conservative and Labour MPs are set to defect to Ukip following Douglas Carswell shock move from the Tories.
While on the campaign trail with Mr Carswell in Clacton this morning, Mr Farage said he expected more to jump ship if the Tory defector wins the by-election.
Mr Farage said, "Let's see what happens in this by-election, but if Douglas wins this by-election there'll be others - not just in the Conservatives but on the Labour backbenches too".
Conservative grandee John Redwood has dismissed the "so-called" eight Tory MPs allegedly considering defection to Ukip as "figments of Ukip's imagination".
"Dream on Ukip," the eurosceptic MP for Wokingham and former Wales Secretary told Radio 4's Today programme.
"I treasure the words of Mr Carswell which he was speaking yesterday. He said that we need to deliver an in-out referendum, he said it would only happen if David Cameron was prime minister," Mr Redwood said.
"He said we must do nothing to make the prospect of a referendum less likely. He was super-loyal until yesterday."
Ukip leader Nigel Farage and his new recruit Douglas Carswell are in Clacton as the pair plan a completely unexpected by-election campaign.
They are visiting the seat after Mr Carswell's bombshell decision to switch parties and quit the Commons to re-stand under the Ukip banner.
The rebel Conservative MP Douglas Carswell delivered a double blow to his party today - a shock defection to Ukip and he has forced a by-election in Essex which many believe the Tories are likely to lose.
The deeply Euro-sceptic Mr Carswell, who is the MP for Clacton, was unveiled as Ukip's newest recruit in a press conference in London. He said he was defecting from the Tories because Mr Cameron was not serious enough about the change needed in Britain's relationship with Europe.
He will resign as an MP when Parliament returns next week, forcing a by-election which could see him returned as Ukip's first ever elected member of parliament.
Click below to watch a full interview with MP Douglas Carswell:
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Prime Minister David Cameron has described Tory MP Douglas Carswell's defection to UKIP as "deeply regrettable" and "self-defeating".