Charles Kennedy has insisted his party's stance on Iraq and top-up fees have been vindicated, in a bullish conference speech.
Mr Kennedy showed signs of illness during his speech
Ignoring speculation about his health, he told delegates they were in the party of the moment and said he was up to the challenges of the year ahead.
Mr Kennedy - showing obvious signs of the stomach illness that laid him low during last week's Budget - spelled out big differences between the Lib Dems and their political foes.
He focused in his 40-minute address to delegates in Southport on "opportunist" Tory leader Michael Howard, claiming his brand of conservatism offered a "nightmare scenario".
He told the spring conference that "trust" in prime minister Tony Blair had been eroded by the Iraq war and "can't be regained in ever the same way again".
"Prime minister, look outwards and don't just look across the Atlantic," he told the Southport gathering.
He contrasted what he said were the failings of the other two parties with "tough decisions" made by the Lib Dems in not supporting the Iraq war, the Butler inquiry into pre-war intelligence, and plans for top up fees.
He put the party on an election footing, predicting the Lib Dems had a "real chance to make a difference" at the local, European and London mayoral elections on 10 June.
But it was the Tories and their leader that received most of Mr Kennedy's ire.
He claimed Mr Howard had made "four gaffes in four months" over issues including the Hutton inquiry, the Butler inquiry, benefit withdrawal for asylum seekers and controversy in the immigration department.
He said the new name for "opportunism" was Michael Howard, arguing his honeymoon period as new leader was over despite "all the hype, all the hope".
While levels of support for the Tories was still roughly where it was when William Hague quit as leader in 2001, the Lib Dems were on average 10% higher in the polls than they were at the same time in the last Parliament, he said.
Support had been gained from students and British Muslims, the party was "neck and neck" with the Tories at the local level and had seized Brent East from Labour.
He called for a new approach to dealing with international terror, claiming it was unhelpful to use the "rhetoric of war" to describe what was happening.
He said the international community was better placed to deal with situations like Iraq.
KEY CONFERENCE DECISIONS:
Scrap council tax
Allow 16-year-olds access to porn
Scrap top up fees
Allow doctors to medically assist suicide
Terrorism should be confronted by the gathered wisdom, expertise and support of all friendly nations "not just the views of our only superpower".
Banging the drum of his party's "fairness" theme, Mr Kennedy hailed its policies to scrap the council tax, tuition fees, provide free personal care for the elderly, cut bureaucracy and a new approach to dealing with crime.
The Lib Dems would also lead a "radical plan for a greener Britain" and a "green economy", improving the efficiency of cars and developing alternative fuels.
Mr Kennedy said the party should have "confidence" in its outlook, principles and ability to deliver, pointing out that Lib Dems already shared government in Scotland and had power in councils across the country.
"When we stand up for what we believe in, as we did over the war in Iraq, we get respect. We must build on that," he said.
Earlier Simon Hughes, the Liberal Democrat spokesperson on London and mayoral candidate, told BBC's Breakfast with Frost programme the party leader's health was not in question.
He denied Mr Kennedy's illness was linked to stage fright, as some commentators have suggested.
"He is ready for the speech and appears to be well on the way to recovery," Mr Hughes said.
"He's not quite 100%, but he's ready and everything is back to normal."