Ditch 'Blu Tack and cardboard' funding system, says Jones
First Minister Carwyn Jones has called for a new funding system that meets the needs of public services in Wales.
It sets him against Downing Street and his own party's leadership, which has said it will keep the existing system.
The UK government uses the Barnett formula to decide the size of its funding to the Welsh government.
Mr Jones said the formula, devised in the 1970s, was "the constitutional equivalent of fixing a hole in the roof with Blu Tack and cardboard".
Labour has said it would make adjustments to help Wales, but Mr Jones again called for a new formula based on the UK nations' and regions' needs.
Welsh Secretary Stephen Crabb said David Cameron had "started a process led by William Hague to look at all these issues".
'Drop of a hat'
In a speech in London on Wednesday, Mr Jones said: "Scotland gets promises made to it at the drop of a hat. In Wales we have to wait more than a year."
The Welsh government has said it is short changed by around £300m a year under the current arrangement.
Prime Minister David Cameron recently told BBC Wales: "There aren't plans for some huge change in the formula distribution."
Meanwhile, Labour has said it would meet the Welsh government's call for "fair funding", but has ruled out scrapping the Barnett formula.
Together with the Conservatives and the Liberal Democrats, Labour committed to retain the formula as part of the Scottish independence referendum campaign.
Analysis by political correspondent Daniel Davies
While there is talk at Westminster of topping up Welsh government funding, both David Cameron and Ed Miliband have said they will keep the Barnett formula.
So it would appear that, on the face of it, Carwyn Jones is unlikely to get a new funding formula, one that he argues should be fairer to Wales and some other parts of the United Kingdom.
Yet the first minister maintains that, eventually, this issue is going to have to be sorted out properly, for the good of the UK as a whole.
Labour is proposing a constitutional convention to tackle the thorny devolution issues, something the UK government is leaving the door open to.
Mr Jones has long proposed such a convention, "including a variety of opinion formers and members of the public", and perhaps that is his best chance of getting the formula he wants.
But Mr Jones said a more fundamental overhaul for the whole of the UK was required.
He said it was not a case of "special pleading or saying to Scotland 'give us your money'".
He added: "It's very difficult to make a logical case for the retention of Barnett as it is.
"In the meantime I would say - selfishly - fine, as long as we've got the money in Wales then we're fine... (but) at some point in time there's going to have to be an examination of Barnett."
It was a "fundamental principle of the Union that money is distributed to where it's needed at that time", he said.
His speech called for a "new Union mindset" and "more federal thinking in the UK".
Mr Jones attacked moves towards English votes for English laws in the Westminster Parliament, and said further devolution promised to Scotland during the referendum campaign had to be honoured.
Responding, Mr Crabb said: "The prime minister has started a process led by William Hague to look at all these issues.
"There are meaty decisions to make and so it's so important that we allow the Hague committee the time it needs to get it right.
"That's why I've begun a process to establish the views of the Welsh parties to feed into the debate."
Also on Wednesday, Mr Jones's predecessor Rhodri Morgan delivered a speech in Cardiff calling for a new funding system and an elected House of Lords.
He said the principle of the funding formula should form part of a new written constitution for the UK.