Denver, Colorado  - Senator Hillary Clinton, who brought her presidential bid within a hair's breadth of winning her party, was expected to appeal later Tuesday for her 18 million backers to get solidly behind rival Barack Obama in the general elections.

But ahead of the much-awaited speech before 4,400 Democratic Party delegates in Denver on Tuesday, many supporters continued to be unhappy about a prospect of forced unanimity and were trying to force a state-by-state roll-call vote the next evening.

Many in the Obama camp fear such a display of support for Clinton, who won more than 40 per cent of delegates in primary elections, could undermine the party's bid to reclaim the White House in November.

Tension between the Obama and Clinton camps over the plan has become fodder for media speculation, even as the New York senator on Monday tried to publicly quell the spat.

"This is Barack Obama's convention as it should be," she said in broadcast remarks. "What we are doing is bringing everyone together with the same level of commitment."

She warned it would be a mistake for her supporters to vote for Republican presumptive nominee John McCain in the general elections.

"Anyone who voted for me has so much more in common with Senator Obama" than with McCain, she said.

Yet her supporters are still pushing for the formal recognition of her accomplishment as a woman who went further in her bid for the party's presidential nod than any woman in US history.

And some say they will defy her request and that they won't be railroaded into voting for Obama Wednesday night in the roll-call vote.

Maryland State Senator Mary Boergers, a diehard Clinton delegate, said there's a move afoot to collect 800 signatures that could force a rules fight over the state-by-state roll call that the Obama campaign is apparently trying to cut short with a rules manoeuvre.

"I respect what (Clinton's) saying. I have a different path to unity," Boergers told Deutsche Presse-Agentur dpa.

The Clinton dynasty already dominates two evenings of the four-day gathering that will end Thursday with Obama's acceptance speech before 75,000 people at Ivesco field's Mile High Stadium.

Her speech Tuesday evening will clinch an evening designed as a salute to Clinton, complete with a video prologue, and to women's accomplishments in politics. The day marks the 88th anniversary of women's right to vote in the US.

Clinton is not, however, delivering the so-called keynote speech, to be given by former Virginia governor Mark Warner who is locked in a hard battle for election as US senator. In 2004, Obama rose to national promise when the party gave him the "keynote" role to boost his chances of winning a US senate seat held by a Republican.

On Wednesday, before the roll-call vote, Clinton's husband, former president Bill Clinton, is to speak.

Boergers likened the "huge pressure" on Clinton delegates to switch to Obama, to Russian Prime Minister Vladimir Putin's "Kremlin" tactics.

"Whoever doesn't go along with the programme is subversive," Boergers said. Obama's people "seem to be terrified of having the votes counted."

Boergers said she feels an obligation to her Maryland voters to cast her ballot for Clinton.

Clinton is "going to tell us to vote for Obama? It's not up to her to convince me to vote for Obama. It's up to Obama to do this." (dpa)