Jo Swinson has repeatedly apologised for her role in austerity measures under the Lib Dem-Conservative coalition after she was pressed in a BBC interview over why her party is seeking to roll back several measures she voted for in the 2010-15 administration.

“I am sorry that I did that. It was not the right policy. And we should have stopped it,” the Lib Dem leader said, when asked by Andrew Neil if she wanted to apologise to people affected by the bedroom tax, saying her party would reverse the policy.

Swinson, who is facing criticism of her tactical decisions and voter appeal in a campaign which has seen the Lib Dems’ poll rating gradually slip, also said she would remain as leader even the party ended up with fewer than the 21 MPs they began the election with.

“I’m continuing as Liberal Democrat leader,” she said. “I’ve got a job to do and I’ve just been elected to do it.” Asked if she would remain regardless of the result, she replied: “I’m here to stay and we’re going to get a great result.”

Swinson is among the leaders of all the main political parties to undergo a grilling from Neil, with the exception of Boris Johnson, who is refusing to agree to an appearance.

The quizzing on benefit cuts began with Neil noting that the Lib Dems wanted to scrap the bedroom tax, which cuts benefits for people living in social homes with more rooms than they are deemed to need. “Who voted nine times to introduce the bedroom tax?” he asked.

“The Liberal Democrats in government, including myself,” said Swinson, who held various junior ministerial roles from 2012 to 2015. She added: “Which I have previously said – and I’m happy to say again – was wrong. And I’m sorry about that, and it was one of the things that we did get wrong.”

Is Jo Swinson's election campaign punching below its weight? Read more

Swinson also acknowledged that while in the coalition she backed the benefits cap, which limits the maximum benefits income a family can receive regardless of circumstances, and private tendering in the NHS – all of which she now wants to reverse.

Asked why voters should trust her, Swinson said: “Clearly we didn’t win every battle against the Conservatives. We fought many battles and we did win battles for more money for schools, for more money for the poorest pupils, for managing to cut tax for the lowest paid. To introduce same sex marriage. There’s many things that I’m very proud of where we made a difference.

“But of course, of course there were things where we didn’t win those battles, and I’m sorry about that. It was not a Liberal Democrat government, it was a coalition government.”

Swinson has faced criticism for beginning the election campaign with the argument she could become prime minister. Asked about this by Neil, she said: “Clearly, when you look at the polls that’s not the most likely scenario. I will certainly grant you that.”

Play Video 1:06 Extinction Rebellion bee protesters 'swarm' Swinson battlebus – video

Earlier on Wednesday, a campaign visit by Swinson to a youth centre in Streatham, south London, was disrupted by protesters from the Extinction Rebellion protest group, dressed as bees. One of the activists glued his hand to the windscreen of the Lib Dem battle bus.

Extinction Rebellion is targeting every party. Other members, also dressed as bees, lay on the floor of the Brexit party’s office in Grimsby, while others later glued themselves to the Brexit party bus.

Swinson met the protesters, arguing with them that the Lib Dem’s target of becoming carbon neutral by 2045 was realistic and could be shortened as technology advanced.