He said he seriously considered joining Ukip last year, but believes that the popularity of Nigel Farage's party may now have peaked.
Mr Pritchard, who has represented The Wrekin since 2005, said it was only when Mr Cameron announced his plans for an in-out referendum on Britain's membership of the EU in January last year that he decided to remain as a Conservative MP.
The MP, who was last week pictured posing with Ukip leader Mr Farage at a political event, stressed that he is now committed to the Tories.
"Now we have that commitment, clearly it makes sense to make the case as a Conservative MP," he said.
"I am not going to defect to Ukip," he said.
"There was a time when I seriously considered it."
He said that voting Ukip was likely to help put Ed Miliband into Downing Street.
"If I were a Labour political strategist, seeking to get Labour back into Number 10, I would have created Ukip," he said.
"Ukip are Ed Miliband's best political friend."
Meanwhile, North Shropshire MP and former cabinet minister Owen Paterson was today calling for Britain to leave the European Union.
Mr Paterson was due to call on David Cameron to invoke Clause 50 of the Lisbon Treaty, which would trigger negotiations for Britain's withdrawal from the EU.
In an address to the Business for Britain Campaign, former Environment Secretary Mr Paterson will say he wants to see the Government brought back within the control of our the British Parliament.