Q&A: The chair row explained

Presiding officer Dafydd Elis-Thomas and his deputy John Marek had both expressed unwillingness to do it.

If Dr Marek were to chair, the collective opposition would have lost its ability to vote down the budget.

However, Lord Elis-Thomas confirmed he would chair the debate on the �14bn draft budget on Tuesday after all.

The opposition parties has presented a list of a dozen priorities which they say Labour has neglected in its draft budget, published last week.

Labour announced there would be an extra �74m for public services, an extra �9m for public services and an additional �15m for roads.

Dr Marek, an independent AM, is expected to vote with Plaid Cymru, the Liberal Democrats, the Conservatives and independent AM Trish Law against Labour.

'Scarcely believable'

Relations between Lord Elis-Thomas and Dr Marek have been strained for some time over how the assembly should be run after the Government of Wales Bill is implemented next year.

Following a meeting between assembly party leaders on Monday evening, the BBC was given to understand that the collective view was that Lord Elis-Thomas was "likely" to chair the budget debate, but nothing was certain.

If he had gone against his own party's whip, then Labour would have been likely to get the draft budget passed.

Plaid Cymru said it was their "expectation" that Lord Elis-Thomas would take the chair.

It was only finally confirmed he would preside at lunchtime on Tuesday.

Welsh Liberal Democrats leader in the assembly Mike German had called on Dr Marek and Lord Elis Thomas to "bury the hatchet".

Mr German said: "I find it scarcely believable that a row between two experienced individuals could be overshadowing the most important debate of the assembly calendar.

"The budget decides how �14bn will be spent in Wales next year. It is of real and lasting importance to all three million people in Wales. The battle of the presiding office is of lasting importance to just two people."