The backbench Labour MP fired the first shots in what could be a bitter and hard-fought battle against Downing Street's preferred choice as the party's new leader in Wales, Welsh Secretary Alun Michael.

Mr Morgan, currently clear favourite in the opinion polls, said his leadership bid would be based on breaking down barriers and keeping the assembly free of party machine politics and "jobs for the boys".

Alun Michael has had to fight off the tag of being Tony Blair's man

Mr Michael, meanwhile, has strenuously denied suggestions that he has been "parachuted in" by Number 10 Downing Street to succeed Ron Davies, who last month resigned from the cabinet and the Welsh leadership after his unexplained encounter with a dreadlocked man near a known gay cruising spot on London's Clapham Common.

Mr Morgan said: "The assembly belongs to the people, not to the Welsh establishment. Our assembly must be sleaze-free, right from day one.

"May 7 1999" - the day of the first elections for the assembly - "is the day on which Wales stops being administered as a government department and starts being run as a country.

"That must mean few, if any, quangos, no vested interests and no narrow sectionalism."

Among those already publicly backing Mr Morgan's campaign was miners' leader Tyrone O'Sullivan, chairman of the workforce who successfully re-opened Tower Colliery after buying it from British Coal.

"I believe Rhodri is now the natural leader of Wales," he said. "Wales is a radical country and we need radical politics."

Mr O'Sullivan also announced that the Tower miners would hold a ballot on the assembly leadership.

The white-collar Manufacturing Science and Finance union has also announced it will ballot its 12,000 Welsh members before deciding how to cast its vote in the electoral college that will select the new leader.

Fifteen unions and four other affiliated organisations will have a crucial third of the total vote when the Wales Labour party holds the electoral college vote next February.

Although Mr Morgan, the MP for Cardiff West, has strong support in local constituencies among party members, Ron Davies beat him to the leadership last September, picking up most of the union block votes.

Supporters of Mr Morgan say they hope more unions will hold democratic ballots instead of merely "consulting" their members before casting their votes.