Scottish Secretary Alistair Carmichael also said that, overall, the LibDems could even gain Westminster seats in 2015.
In an interview ahead of the party's spring conference in York, which opens today, he said his party had captured the new centre ground of UK politics.
Despite lingering public anger over university tuition fees and the decision to enter a coalition with the Conservatives in 2010, he claimed that history would "judge us well". He added: "But never mind history, I can't wait for history. The electorate will judge us well in 2015."
His comments come as the LibDems continue to take a hammering in the opinion polls. The party is hovering at around 10%, behind Ukip.
Political observers have even suggested that some of the party's most high-profile politicians could lose their seats in 2015.
In Scotland, the party suffered humiliation in the Holyrood elections a year after it entered into the coalition at Westminster, losing 11 of its 16 seats.
But Mr Carmichael said his party was perfectly positioned for the election. Employing a golfing metaphor, he said: "We are in the sweet spot of British politics. Nobody believes that Labour have any economic credibility left.
"But at the same time nobody believes that the Conservatives have the political instincts, pressures or motivations to grow the economy and share the proceeds of growth in a way that is fair.
"I think these are the two things that the people of Britain want to see. They want to see the economy back in a healthy state. But they want to see the widest possible range of people benefitting from the health of the economy."
Asked if the party was now occupying the centre ground of politics, he said: "I think I would."
As well as acting as a counterbalance to the other two parties, the LibDem can now point to the party's achievements in government, he said, in a way he could not in 2010.
These include the recent announcement about potential increases to the minimum wage. That could only have been achieved through the coalition, he said.
He said: "LibDems on their own could not deliver that. And Tories on their own would never think of delivering that. So it is an achievement of the government and its one that I am very proud of."
On the next general election he said: "I think I would expect a parliamentary party that is roughly the same size that we have, possibly even slightly bigger.
"That's a realistic ambition for the party. That gives us all sorts of opportunities on the other side of the election. As part of that, I would expect us to hold all our seats in Scotland."
The LibDems have previously announced plans to run a "digging in" strategy next year, hoping to keep seats they currently holds and targeting only a few others.
On issues like tuition fees, where the party was accused of betrayal for its U-turn on a pledge to oppose any increases, the Scottish Secretary said: "We have been judged at different points along the road when we had to make compromises.
"But there is a different judgment at the end of the parliament, which is on the totality. That collective judgment will be favourable to us. History will judge us well. But never mind history, I can't wait for history. The electorate will judge us well in 2015."
A Labour source said: "Alistair Carmichael's comments are just more proof of how out of touch he is."