Jo Swinson has apologised for voting to cut benefits while serving in government with the Conservatives.
The Liberal Democrat leader told the BBC’s Andrew Neil her party had been wrong to back the so-called bedroom tax in the coalition government and “we should have stopped it”.
Although some cuts were needed when her party came into office in 2010, she suggested austerity had gone too far.
Her party was committed to spend more on welfare and childcare, she added.
During the 30-minute interview, Ms Swinson said she was determined to stop Brexit by whatever means possible, including working with other parties in the event of another hung Parliament to try and get another referendum.
But she conceded the Lib Dems were unlikely to form the next government and be in a position to fulfil their campaign pledge to revoke Article 50 – the legal process for leaving the EU – without a further public vote.
‘Here to stay’
She said she disagreed with her predecessor Sir Vince Cable that the pledge had become an “unhelpful distraction” for the party, which has found itself being squeezed in the opinion polls during the campaign.
Having only been elected leader in July, she insisted she was “absolutely here to stay” whatever the outcome on 12 December.
Ms Swinson was repeatedly challenged on her party’s record in government between 2010 and 2015 and her personal backing for cuts to benefits and Sure Start children’s centres.
She acknowledged she had voted nine times for the bedroom tax, the controversial policy which saw working-age families in council or housing association homes docked housing benefit if they were deemed to have more bedrooms than they needed.
Ms Swinson, who served as a junior business minister in the Lib Dem/Conservative coalition between 2012 and 2015, was asked whether she would like to apologise to 240,000 of the poorest in society who suffered financially as a result and, in some cases, were forced into hardship.
“Yes, I am sorry I did that,” she replied. “It was not the right policy and we should have stopped it…I have previously said – and I am happy to say again – [it] was wrong. I am sorry about that and it is one of the things we did get wrong.”
Asked about other welfare changes she backed at the time but is now committed to reversing, such as a cap on the overall amount of benefits a single household could receive, she said she had voted for them “as someone with collective responsibility in government”.
She said her party had “won many battles” with the Conservatives, such as in securing more money for children from disadvantaged backgrounds and taking many of the lowest paid out of income tax.
But she said she accepted the public services had borne too much of the brunt of the government’s drive to slash the deficit in the public finances.
“I am not going to say in a financial crisis that it was going to be possible with the deficit at the level it was in 2010 not to make any cuts at all,” she said.
“Some cuts were necessary but the shape of those cuts, the balance between cuts and tax rises I don’t think was the right balance.”
Labour have long argued that austerity was a political choice and not a financial necessity. Ms Swinson said cuts were unavoidable and the level of retrenchment under the coalition mirrored the plans set out by Labour in its 2010 manifesto.
But pressed by Neil on whether austerity was a “necessary evil or terrible mistake”, she replied: “Clearly too much was cut, clearly not enough was raised from taxation.
“And certainly the investment should have kicked in earlier in terms of more borrowing for capital investment.”
But she said these decisions were “almost a decade ago” and her party was now committed to scrapping the bedroom tax and addressing in-work poverty by reversing cuts to work allowances for families on Universal Credit and helping families with two earners.
She said the £14bn the party was planning to spend on expanding free childcare – by funding 35 hours a week of provision for all children aged two to four – “more than replaces the money that was cut” during the coalition years.
“We have a plan for the future which identifies what our priorities are…and we are being upfront about where the money will come from.”
In a special series of election interviews, Neil has already questioned Labour leader Jeremy Corbyn and the SNP’s Nicola Sturgeon, His interview with Brexit Party leader Nigel Farage will be broadcast on Thursday.
Prime Minister Boris Johnson has yet to agree a date to taking part, which has prompted a political row and accusations from Labour that he is “running scared”.
The SNP launched an attack on Ms Swinson’s record as part of the coalition government, following the interview.
The party’s Pete Wishart said: “Despite Jo Swinson’s best attempts to dodge her shameful record when in government with the Tories, the reality is communities across Scotland will not forgive or forget the Lib Dems for their active part in inflicting austerity on the most vulnerable people in society.”