Ed Miliband has vowed to turn his fight to win back a Labour seat after Tory MP Louise Mensch stood down into a "crusade for young people".
The Labour leader was in Thrapston, near Corby in Northamptonshire, yesterday where he pledged to knock on every door in a bid to win votes in a forthcoming by-election.
A cheer went up from some of the 30 gathered Labour supporters when he told them he would make unemployment a key battleground issue in the campaign.
He told the group: "I make this promise about this campaign – we are going to be visiting every door in this campaign, whether people voted Tory, Liberal Democrat, Labour or didn't vote at all.
"Less than half the people voted at the last council election – we've got to reach out to them. We've got to reach out to people who are turned off politics.
"We've got to make this campaign, and we are going to make this campaign, a crusade for the young people of Corby, a crusade for people right across Corby."
Mr Miliband was in the Corby and East Northamptonshire constituency to launch his party's campaign to try to snatch the seat from the Conservatives.
Prime Minister David Cameron, whose party is at a low ebb in the polls against a resurgent Labour, faces a stiff challenge to retain Mrs Mensch's seat, but the Conservative vote has remained strong in recent council elections.
Mrs Mensch – then Louise Bagshawe before her marriage last year – won by only 1,951 votes in the 2010 general election. Labour had previously held the constituency since 1997. The mother-of-three announced on Monday her intention to leave Westminster and move to the United States with her family.
The backbencher, who shot to prominence as a member of the Culture, Media and Sport Select Committee which investigated the phone-hacking scandal, said she was "devastated" but that it was a "necessary decision".