Plaid Cymru has tabled a motion of no confidence in Assembly First Secretary Alun Michael.

The motion - supported by the Conservatives and Liberal Democrats - followed a debate to ratify the National Assembly's budget.

Worded simply, the motion read "The National Assembly has no confidence in the First Secretary".

Assembly Members will debate the no-confidence motion on Wednesday at 1430GMT before Mr Michael replies, then a vote will be taken between 1515-1530GMT.

If the vote is carried, the Labour party will hold an emergency meeting to decide on what course of action to take next.

The motion was signed by the three opposition party leaders and group business managers.

Plaid's Acting Leader Ieaun Wyn Jones said Mr Michael had "let Wales down badly".

Mr Michael is accused by opposition parties of failing to secure additional funding for Wales under the Objective One European regeneration scheme.

"Mr Michael should have made the case for Wales to get the money it deserves much more strongly," said Mr Jones.

"He has been reluctant to battle with the Treasury and his hotline to Tony Blair has gone cold. Tony Blair and Gordon Brown have also made it clear that they are letting Wales down.

"The people of Wales realise this and this is why we are confident that the people of Wales are behind our actions."

Mr Michael said the vote was tied in to a "meaningless and arbitrary deadline".

"The money is there and we have been consistent and honest in our explanations.

"For the following years we are negotiating with the Treasury as part of the Comprehensive Spending Review now under way.

"I am determined to get the best deal for Wales and will continue with colleagues to negotiate hard on behalf on West Wales and the valleys."

Meanwhile, Economic Development Secretary Rhodri Morgan acknowledged that Mr Michael may not be First Secretary in a week's time.

Mr Morgan - who lost out to Mr Michael in a party leadership contest - said he thought the First Secretary would survive.

"But to some extent it depends on procedure and the rules for those procedures have not yet been written," said Mr Morgan.

"The phrase 'unchartered waters' is hardly adequate to describe the uncertainty of what will happen over the next seven days."

Earlier, a former government minister urged the Assembly First Secretary Alun Michael to resign.

Cardiff Central MP Jon Owen Jones told the BBC that Mr Michael was "extremely unpopular", and that making him the party leader in Wales had been a "mistake".

Mr Jones said Mr Michael's resignation would be the only way for the Labour Party to recover its reputation in Wales.

"It's not an exaggeration to say the future of the Labour Party in Wales is at stake," he said.

"What we have to do is decide whether we want to continue to face further punishment or whether we should move on.

'Stand aside'

"To move on, it requires new leadership and I think that Alun should stand aside."

Plaid Cymru has insisted on the Treasury providing match-funding for a £1.2bn aid package and claims Mr Michael has failed to achieve that guarantee.

The European funds - earmarked to help regenerate deprived areas - can only be accessed if pound-for-pound matching cash is made available.

Party president Dafydd Wigley confirmed on Monday that the no-confidence vote would go ahead after Chancellor Gordon Brown rejected calls for extra funds, saying all the money is already in place - within Wales's block grant.

Mr Michael insists he will not stand down even if he loses a vote of no-confidence.

"I am the leader of the Labour Party in Wales and its nominee for First Secretary and nothing has changed around that," said Mr Michael.

The Opposition parties warned they would push ahead with further no-confidence motions should he be renominated by his party.