Mr Jones wants more spent on education

Ieuan Wyn Jones said it was "absolute nonsense" to suggest he had backed away from opposition plans to form such a government before that date.

He was speaking on the BBC's Politics Show days before Labour is due to present its budget to the assembly.

Opposition parties have threatened to vote it down over spending differences.

They want an extra �22m put into education, and had suggested they would be prepared to form a coalition government if First Minister Rhodri Morgan were to step down following a defeat.

You can't have a coalition government for four months Ieuan Wyn Jones

However Mr Jones told the programme that this suggestion was "never on the cards".

"I never said I wanted to wreck the budget or bring the government down. I just want more money for schools," he said.

"Rhodri Morgan has said he won't resign if he loses the budget."

He added: "You can't have a coalition government for four months."

The reality was that no party "was likely to gain a majority" in the assembly elections next year, he said, and he indicated he would be willing to lead a government if necessary.

"Under these circumstances, of course you have a responsibility but we can't talk about it before the election because every party needs to make sure that its own policies are put forward at that election," he said.

He added the current priority was to ensure more money for the assembly's schools and university budget and that the assembly government needed to discuss the issues with the opposition.