Sir Menzies Campbell said it was up to Welsh Liberal Democrats if they wanted to go into coalition with other Welsh Assembly parties.
He said he would not dictate to his party's Welsh wing if there was no outright majority in the Assembly after next year's election.
On the eve of the Welsh Lib-Dems conference he said, "It's a matter for the (Lib-Dem) group to decide how best to represent the people of Wales.
"It's for those who are elected to determine how they think the people of Wales can best be served."
And he insisted there would be no rightward shift under his leadership.
"There's no question of a shift to the right. I'm a politician of the centre left," he told ITV Wales.
He said he wanted to maintain the party's "traditional values" but give them "contemporary relevance".
The Lib-Dems - the smallest party in Cardiff Bay - were in coalition with Labour in the Assembly between 2000 and 2003. Their best chance of power in 2007 is likely to be in another joint administration.
Meanwhile, party president Simon Hughes last night said allowing Welsh and Scottish MPs to vote on English issues was "unacceptable".
Mr Hughes, who was defeated in the race to lead the Lib-Dems, said it was time to change the rules, which caused "growing resentment" in England.
But Sir Menzies - himself a Scottish MP - insists there should be no reform without a wider overhaul of the constitution.
Sir Menzies has said there should be no "knee-jerk" reaction to a series of knife-edge votes at Westminster.
The question of who should vote on which issues has risen up the political agenda in recent weeks as Prime Minister Tony Blair attempts to force through controversial reforms.
Some only apply in England but need Welsh and Scottish MPs' support to clear the House of Commons.
Yesterday Lord Falconer, the Lord Chancellor and a key Blair ally, said calls for a ban on Welsh votes on English issues were based on a "misunderstanding of devolution", and rejected the idea of an English parliament.
But Mr Hughes, who grew up in Cardiff and Brecon, said, "Lord Falconer and the Government are putting their heads in the sand.
"The present Constitutional arrangements for making English decisions are unacceptable and need to be changed.
"There may not be massive demand for an entirely separate and new English parliament, but there is growing resentment at England-only issues being decided by politicians from other parts of the United Kingdom.
"This issue will not go away, and the Liberal Democrats are determined to make sure it doesn't."
Sir Menzies wrote in a newspaper in January, it would be "a grave mistake to tinker with one aspect of our constitutional arrangements in isolation."
In a speech in London yesterday Lord Falconer said the aim of devolution was "not to change the role of the national parliament. It was to provide the Scots and the Welsh with constitutional protection which the English, as over 80% of the population and the MPs, did not require.
"This misunderstands the role of Parliament, the role of an MP and the nature of legislation," he said.
MPs were in parliament to represent the UK as a whole, and there could be only one "class" of MP in that parliament, he said, adding, "The political reality is that any party purporting to be a national party must obtain as many votes as possible in England.
"Devolution protects Scotland and Wales from proposals for which there is no support in those countries."
The Liberal Democrats meanwhile, hope to use the conference as a springboard towards a strong performance in next year's Assembly elections.
Delegates will vote on whether to retain the flagship promise to replace council tax with local income tax.
Page 2- Lib-Dems' coalition road to power