Washington - Hillary Clinton does not see herself as a loser. On the contrary, the closer she gets to the Democratic Party convention that opens Monday in Denver, Colorado, the more self- confident she appears.

A couple of weeks ago, the face of the former first lady still showed the marks of disappointment and the strains of the primary campaign.

However, she is shining once again. Even her laughter sounds clear and triumphant. It is the laugh of a woman who is aware of her own power: if she gives him the thumbs-down, Barack Obama might never reach the White House on November 4.

She and her husband, former president Bill Clinton, will play key roles in the Democratic Party convention in Denver, perhaps to answer what her legion of fervent supporters are wondering: Does Hillary Clinton want sincere reconciliation or belated revenge?

On the outside, the 60-year-old US Senator leaves no doubt of her loyalty to Obama as the nominee of their centre-left party.

"We may have started on different paths, but today our paths have merged," Clinton has said.

She sounds like a loyal party soldier, and she has even made campaign appearances for Obama. Clinton vows to be doing her utmost to help her former rival reach the White House.

However, columnists warn that the Clintons keep casting doubts about Obama.

"Yes, she can" was a recent headline in The New York Times, a play on Obama's campaign slogan, which was intended to read as "yes, she can mess things up for Obama."

"Whatever insincere words of support the Clintons muster, their primal scream gets louder: He can't win! He can't close the deal! We told you so!" op-ed columnist Maureen Dowd wrote.

Dowd described the Clintons' feelings with a German word sometimes applied in English: "Schadenfreude," or joy at others' sorrow.

In fact, Hillary Clinton has taken a deep fall. She was once a strong favourite to winning the Democratic nomination and was way ahead in intra-party opinion polls. The couple had already lived in the White House for eight years, and a return seemed like destiny - a new dynasty in US politics.

But then the dream was destroyed, lost to a black candidate who was only elected to the US Senate in 2004.

However, Clinton knows her own power. She keeps bringing up the "18 million men and women" who voted for her in the primaries and made her the first woman in US history with a real chance to reach the presidency.

Such an accomplishment could not be brushed aside so easily, despite Obama's eventual victory in the nomination fight.

According to some opinion polls, as many as one in five of Clinton's supporters in the primaries are threatening to withhold their vote for the Democratic nominee in November. Some have even said they would rather vote for centre-right Republican John McCain over Obama.

The trend set alarm bells ringing within the Democratic Party. Obama finally conceded a major speaking role for the former first lady, who will address the convention on Tuesday night. She will even be allowed the unusual step of hearing her name placed in nomination for the state-by-state roll call vote on Wednesday night.

Thomas Mann, an scholar of US politics at the centre-left Brookings Institution, a Washington-based think tank, says that Hillary's prominence at the convention should not be a threat to Obama.

"It was a very close contest. She has many supporters at the convention and in the country, a number of whom have taken the loss very hard," Mann said. "I would say her presence is quite important."

Nonetheless, some protests are expected in Denver. One group calls itself PUMA (Party Unity My Ass). Another group plans a parade and rally Tuesday in Denver to celebrate Clinton's accomplishments.

"Hillary will try to show the Democrats they chose the wrong savior," Dowd wrote.

For some Clinton loyalists, her high profile in Denver has been balm on their wounds.

Mary Boergers, 62, a Maryland state senator who organized for Clinton during the state's primary election, said she had initially felt depressed about going to the convention when it appeared Hillary would be shut out of a major role in Denver.

"I don't remember ever as a delegate feeling bad about being at a convention and supporting my candidate," Boergers said. Obama needed "to be pulling people together and not mashing them into the ground."

But when she heard that Hillary would allow herself to be nominated, "it was the first I got excited about going."