After Hillary, Bill Clinton's turn to boost Obama

DENVER (Reuters) - Bill Clinton once vowed to fight for voters "until the last dog dies." On Wednesday he shows how hard he will fight for Democratic presidential hopeful Barack Obama on the Clintons' last big day of the 2008 campaign.

The former president's prime-time speech is the capstone on an eventful day at the Democratic National Convention, which will formally nominate Obama, 47, as the Democrats' candidate to face Republican John McCain in the November 4 election.

After a campaign stop with veterans in Billings, Montana, Obama will arrive in Denver, where he will accept the Democratic nomination on Thursday.

Hillary Clinton, 60, who lost to Obama in a protracted primary battle but threw herself behind him unequivocally in a well-received speech on Tuesday night, is expected to free her delegates to back Obama on Wednesday.

"Barack Obama is my candidate," she said to roars of approval in a speech that left no doubt of her desire to set aside grievances and seek party unity. "And he must be our president."

In a symbolic gesture, she will be formally nominated on Wednesday as a way of honoring her and placating her supporters, some of whom have been complaining loudly that Obama did not pick her as his vice presidential running mate.

Sign-waving convention-goers, seeking eagerly to win back the White House after eight years of Republican George W. Bush, will also hear from the man who will likely lead the attack on McCain, Obama's vice presidential running mate, veteran Delaware Sen. Joe Biden.

This comes at a time when Democrats are honing a message aimed at accusing McCain of being out of touch with everyday American economic concerns because he and his wealthy wife, Cindy McCain, own seven houses.

But the event with the most potential for drama will come when Bill Clinton takes the stage.

More so than his wife, Clinton has had trouble reconciling with Obama after a primary feud in which Obama, who would be America's first black president, accused Clinton of injecting racial politics into the campaign.

"There is still work to do on the Bill Clinton front," Howard Wolfson, former Hillary Clinton senior campaign strategist, wrote in The New Republic this week.

Sometimes known in the American media as "the Big Dog," Clinton capped a comeback in his 1992 presidential campaign by promising to fight for New Hampshire voters "until the last dog dies."

Some Democratic delegates at the convention believe that in the end, the Big Dog will bark loudly on behalf of Obama.

"Bill Clinton's feeling are hurt. His ego is bruised," said Brandon Hines, who, at 20, is Michigan's youngest delegate. "I think he will come around for Obama."

The ex-president could be seen tearing up on Tuesday night as he sat in the audience and applauded as his wife asked her supporters to back Obama.

Republicans who have set up an outpost in Denver to hector Democrats have been trying to exploit any signs of division in the Democratic Party.

After running behind Obama in public opinion polls for months, McCain expressed surprise that he had pulled ahead of the Democrat in a Gallup daily tracking poll that had him leading 46 percent to 44 percent.

The mild slide for Obama, which came despite his naming of Biden as his running mate, has generated some anxiety among Democrats who feel he needs to aggressively attack McCain, a chore Hillary Clinton seized with alacrity.

"Now John McCain is my colleague and my friend. He has served our country with honor and courage. But we don't need four more years, of the last eight years," she said.

(Additional reporting by Thomas Ferraro; editing by Patsy Wilson and David Wiessler)