Sacked Liberal Democrat minister Jeremy Browne has hit out at party leader Nick Clegg's "blurred liberalism", in a media offensive raising eyebrows in Westminster.
The former Foreign Office minister, whose book Race Plan is published this week, suggested this morning that Clegg had been forced to "meet his detractors halfway" and that this had undermined the coalition's junior party.
"I regret if people don't think the Liberal Democrats are liberal," he told the Today programme.
"I think that is a real challenge for our party as to why a lot of people who have liberal views don't see the Liberal Democrats as their natural home."
He revealed he regretted the coalition had not been more ambitious and blamed his own party for having held back the Conservatives' agenda.
"I think my party deserves a lot of credit because we woudn't be seeing the economic recovery unless the Liberal Democrats had shown resolve," Brown added.
"But I am nervous sometimes that the party seems sometimes more comfortable being a brake on the government rather than an accelerator... I'd like the Liberal Democrats to rediscover some of our zeal for authentic reforming liberalism."
Browne singled out Clegg's ally David Laws, a co-author of the Orange Book which bolstered the economic liberal wing of the Lib Dems in the early 2000s, for praise, calling him a "deep-thinking politician" with a "great leadership of the national debate".
He also positioned himself close to Blairites in the Labour party, saying he was sorry Ed Miliband had "pushed them to the margins".
Browne was sacked by Clegg last autumn in a surprise move, setting him up as a key figure on the right of the party.
In a separate interview in which he was even more outspoken about the "chronic weakness" of his party, he told the Telegraph he opposes the living wage, wants the top rate of income tax cut to 40p and backs an end to the ring-fencing of government spending.
"Our lack of self confidence and our willingness to be defined as being a party of timid centrists rather than bold liberals means people look at us and may be reassured that we will be a brake on the other two, but that's hardly a reason to vote for us," he said.
"Nick Clegg took a risk to take us from being party of protest to party of government, but we look like we've turned into a party of protest in government...
"I am certain in my own mind that authentic, unleashed, liberalism is what Britain needs. The problem my party has is we lack the confidence to champion that, despite having liberal in our title. That contributes to our chronic weakness in the eyes of the public who are uncertain what we stand for."
Pollster YouGov placed the Lib Dems in fourth place nationally in its weekend poll for the Sunday Times. Clegg's party stood at nine per cent, with Ukip on 12%, the Conservatives on 34% and Labour on 39%.