Willie Rennie: Jo Swinson backed Tory welfare policies that 'should never have happened'

However he said Ms Swinson had no choice but to back them, given she was a member of the government, and insisted the LibDems were “stronger” for the experience.

“We have learned from those mistakes,” he told BBC Radio Scotland.

The SNP said Ms Swinson, now the UK LibDem leader, should apologise for her actions.

Appearing on Good Morning Scotland, Rennie was asked about his party’s record as part of the Coalition led by David Cameron.

He said: “We’ve made it clear that a lot of the things we were required to vote for we didn’t want and would never have done if it was a Liberal Democrat Government.

“Of course we recognise the mistakes, and I tell you we are stronger for it because we understand the mistakes we made when we were in Government.”

He went on: “We’ve learned an awful lot from being with the Conservatives, and that is why we are now a stronger party that is growing in the opinion polls, that wants to stop Brexit and want to build a brighter future.

“I can tell you we are a professional party that understands the challenges of being in Government and Jo Swinson has got that experience – she’ll be a great leader of this country and that is why I have got confidence in her.”

Later, on Radio Scotland’s Mornings with Jackie Brambles, Mr Rennie added: "In terms of the welfare stuff, there was some stuff as part of the coalition we had to vote through.

"There are a lot of things we managed to achieve in return.

“There are some regrets I have, of course I have that, I think the 'bedroom tax' should never have happened and said so at the time."

He added: "Yes, I regret some of the things but I can tell you we're a stronger party as a result because we understand much more about the hard choices you have to make in government and it has been really instructive for us in terms of our current campaign to stop Brexit.

"We are resolute in trying to stop doing the damage the Conservatives can do to our country. They are hell bent on this dangerous Brexit."

Ms Swinson was a business minister from September 2012 to May 2015.

She consistently voted in favour of the Welfare Reform Act which introduced the bedroom tax, a charge on spare bedrooms in homes relying on housing benefit, in 2013.

Amy Callaghan, the SNP candidate in Ms Swinson’s East Dunbartonshire seat, said: “Jo Swinson was a leading architect of the austerity that the country is still suffering from.

“Even Willie Rennie can’t defend Jo Swinson’s appalling voting record. It’s no wonder that ex-Tory MPs feel so at home in her party.

“It’s time for Jo Swinson to face the music and apologise for ushering in a decade of austerity in Scotland, for cuts to Scotland’s budget, for the Bedroom Tax, and for cuts to disabled benefits.

“It’s time for Scotland to choose a better future as an independent European nation – so we can escape the bleak and broken Westminster system that has failed Scotland time and time again.”

Mr Rennie also claimed voters were suffering from a "scunneration factor" with politics because of years of constitutional wrangling over Brexit and independence.

He said: "Think of the energy that has been absorbed by Brexit and independence over the last few years, it is just out of order and we need to start focusing on the big issues that face our country. We've got a climate emergency - where is the political debate about that?

“It is just not to the level that it should be.”

He added: “I knock on doors every single day during this campaign, in fact I do it all year round, so I understand what people are feeling, that scunneration factor is certainly a new feature and it is as a result of the paralysis over the last three and a half years, in fact I would say since 2011 with the independence campaign as well.

"People just want to focus on what is going to improve their lives, rather than all this distraction and division with the constitutional debate over Brexit and independence."

Scottish Greens MSP John Finnie said: “Willie Rennie claims that the Lib Dems are stronger after propping up the Tories in government for five years, but shows absolutely no acknowledgement of the harm his party facilitated.

“He conveniently forgets that it was his party that first called for a Brexit vote, it ripped up its commitment on student fees, and inflicted callous and inhumane social security cuts that have directly led to destitution and in some cases deaths.

“The Liberal Democrats should be apologising to the voters, instead Willie Rennie wouldn’t even rule out entering another coalition with the Tories.”