Crispin Blunt has resigned from the Conservative frontbench and called on Iain Duncan Smith to step down from the party leadership.

Blunt, who had been a trade and industry spokesman, said Duncan Smith "has not made an impact because he does not have the qualities required."

On the day of the local elections, Blunt's decision to resign and call for another leadership contest has inevitably drawn attention away from Conservative gains at the polls.

Blunt told reporters: "If the electorate perceived us as a credible alternative government the potential support for us could carry us back to government.

"However we carry the handicap of a leader whom Conservatives in parliament and outside feel unable to present to the electorate as a credible alternative prime minister."

Members of the shadow cabinet immediately rallied around the Tory leader.

Tim Yeo, who as shadow trade and industry secretary had been Blunt's boss, tried to play down the importance of the resignation.

"He was a valuable member of my team. I am sorry that he is going. In two days he will be a footnote."

Labour was quick to pounce on this latest bout of Tory in-fighting.

Commons leader John Reid said Blunt's resignation was "symptomatic of a much deeper malaise in the Conservative Party itself which is becoming incapable of being led".