Nick Clegg attacked "draconian" Tories on Monday as he sought to squeeze into the middle ground between David Cameron and Ed Miliband, giving a taste of the Lib Dems strategy for the 2015 general election.
In a speech to mark his fifth anniversary as leader of the Lib Dems, Clegg defended the coalition's plans to cut benefits but said his party had prevented the Conservatives from taking an ever bigger axe to welfare.
George Osborne announced in his Autumn Statement earlier this month that benefit payments would only rise below inflation at 1% in the next three years, a real-terms cut.
The Labour Party has indicated it will vote against the change, arguing that around 60% of those affected will be people in low paid jobs rather than the unemployed.
Clegg tried to chart a middle ground by criticising Labour for opposing a necessary £3.8bn reduction in welfare payments at the same time as slamming Tory MPs for wanting to cut as much as £10bn from the benefit budget.
"The Liberal Democrats are now the party of welfare reform - sensible, centre ground welfare reform," he said.
"Of course, there are some on the right who believe that no-one could possibly be out of work unless they're a scrounger.
"The siren voices of the Tory right who peddle this myth could have pulled a majority Conservative government in the direction of draconian welfare cuts."
Attacking Labour's position he said: "We need welfare protection for people who fall on hard times. Of course. But you cannot ask low-income working people to pay through their taxes for people who aren't in work to live more comfortably than they do."
Harriet Harman Labour's deputy leader, said Clegg was simply trying to distance himself from the record of his government.
"But as ever, with the Lib Dems, they say one thing whilst doing another - resulting in a record of economic failure, trebled tuition fees, nurses cut, police axed and millions paying more while millionaires get a tax cut," she said.
"Bearing this in mind, what we really should be hearing from Nick Clegg today is a proper apology and a declaration that from now on he will actually stick by the promises he makes."
Clegg's speech arguably marks the beginning of the long end of the coalition, as the Lib Dems and Tories begin to slowly decouple from each other ahead of the 2015 general election.
The deputy prime minister will have one eye on his party's lowly poll ratings, as a survey over the weekend showed Ukip had achieved 14%, pushing the Lib Dems into fourth place on 11%.