The Labour MP who led opposition to controversial new terror laws has challenged critics of maverick Conservative MP David Davis to “put their money where their mouth is” and stand against him.

David Winnick (Lab Walsall North) said supporters of legislation allowing police to hold terror suspects up to 42 days without trial should defend their position before voters.

He urged them to stand in the by-election prompted by Mr Davis’ resignation as an MP.

But Mr Winnick also predicted Mr Davis would win the ballot.

The Black Country MP was one of the most vocal critics of the 42-days measures which prompted a rebellion by 36 Labour backbenchers in the Commons last week.

Gordon Brown was saved from defeat only when nine Democratic Unionist Party MPs backed the Government, amid allegations they had been “bought off” with promises of concessions.

Mr Davis stunned Westminster by announcing he was stepping down in protest – giving up his post as Shadow Home Secretary and prompting a by-election in his Haltemprice and Howden constituency.

The decision was said to have left Tory leader David Cameron furious, but Mr Davis has won the support of Labour MPs including Bob Marshall Andrews (Medway) and Ian Gibson (Lab Norwich North), who will campaign for his re-election.

Mr Winnick said he would not campaign for Mr Davis but predicted an easy victory, saying: “Somehow I don’t think Mr Davis will be needing my help.”

He urged supporters of the 42-days proposal to stand for election, saying: “They should put their money where their mouth is, and defend the position.”

Former Sun editor Kelvin MacKenzie announced he was “90 per cent certain” to stand, but it emerged over the weekend executives at News International, the newspaper’s owner, were having second thoughts about bankrolling his campaign. Mr Winnick said: “Kelvin MacKenzie and others should step forward and defend the policy.”

He said Mr Davis had been prompted to act by concern the Conservative Party was planning to shift its position on 42 days detention.

“I think he is trying to stiffen Conservative opposition to the 42-days policy. What has emerged since he made his announcement is two members of the Shadow Cabinet don’t seem very enthusiastic about the position they have taken on 42 days.

“It may be David Cameron was preparing to give his Peers in the House of Lords a nod and a wink to allow it to go through, and the Conservative Party would not repeal it.”

Labour has said it will not decide whether to contest the ballot until Mr Davis formally stands down this week. But it is likely they will not field a candidate.

On Monday, Mr Davis denied his by-election bid was a push for leadership, stating “categorically” he would “never run for leader of the Tory party again”.

He insisted he had put his career on the line because he believed the erosion of liberties was an important issue to make a stand on.

Asked what was David Cameron’s reaction, the former Tory frontbencher said: “He didn’t want to do it. He said it was risky, but he recognised that the risk was primarily mine.”

He added: “It may well be the end of my career.”