Democrats preach party unity on convention eve

DENVER (Reuters) - Democrats preached party unity on Sunday on the eve of a four-day convention to nominate Barack Obama for the White House, with former rival Hillary Clinton preparing to urge her disgruntled supporters to back Obama.

More than 4,000 Democratic delegates and tens of thousands of officials, activists, protesters and journalists descended on Denver for the formal crowning of Obama, a first-term Illinois senator, as the party's leader and candidate for president.

About 1,000 Iraq war protesters rallied at the Colorado State Capitol and marched through the city streets to Denver's basketball arena, site of the first three days of the convention, where they dispersed without incident, police said.

Obama advisers played down the gathering's one potential note of discord -- the continued unhappiness among some supporters of Clinton, the New York senator who was narrowly beaten by Obama in a bitter nominating struggle.

Obama has tried to ease the tension, agreeing to let Clinton have her name placed in nomination and giving her a prime-time speaking slot on Tuesday night. Her husband, former President Bill Clinton, will speak on Wednesday night.

Clinton plans to speak to her delegates on Wednesday morning and urge them to support Obama ahead of a roll call vote on the nomination that night, a Democratic Party source said.

But anger over her treatment flared among her supporters again when Obama chose Delaware Sen. Joseph Biden as his running mate on Saturday -- and apparently never investigated putting her on the ticket.

"Look, he has a high regard for Senator Clinton," Obama adviser David Axelrod said on ABC's "This Week" on Sunday. "But he felt that Senator Biden would be the best fit for him at this time."

Obama spoke with both Clintons this week, and his advisers predicted any bruised feelings would heal by the time Obama delivers his acceptance speech before 80,000 at Denver's football stadium on Thursday.

The speech by Obama, who would be the first black U.S. president, falls on the 45th anniversary of Martin Luther King's "I Have a Dream" speech -- a highlight of the 1960s civil rights movement.

"Senator Obama had a great conversation with Senator Clinton this week as well as former President Bill Clinton. Everybody's on board. And it's going to drive the media crazy when we come out of this convention united," said Obama strategist Robert Gibbs.

Obama, who was on the campaign trail on Sunday in the battleground state of Wisconsin, is running neck-and-neck with Republican White House rival John McCain in most national polls ahead of the November 4 election.

Republicans tried to fan the flames of a possible Clinton feud, launching a television ad featuring a series of her criticisms during the primary campaign.

'SPEAKING THE TRUTH'

"She won millions of votes but isn't on his ticket. Why? For speaking the truth," the narrator said, followed by Clinton's criticisms of Obama's lack of specificity on issues and questions about his relationship to convicted Chicago businessman Tony Rezko, a former fundraiser.

A Clinton spokeswoman noted the senator's clear support for Obama.

"She has said repeatedly that Barack Obama and she share a commitment to changing the direction of the country, getting us out of Iraq, and expanding access to health care. John McCain doesn't. It's interesting how those remarks didn't make it into his ad," said spokeswoman Kathleen Strand.

Obama's choice of Biden, the chairman of the Senate Foreign Relations Committee and one of the party's most respected foreign policy voices, as his running mate was aimed at shoring up one of his biggest weaknesses.

A Washington Post-ABC News poll on Sunday showed just half of registered voters thought Obama has sufficient experience to serve effectively as president. McCain had a 2 to 1 lead over Obama as the candidate with better knowledge of world affairs and the one who would make a better commander in chief.

Biden, a Roman Catholic, also brings strong working-class roots to the ticket that could help Obama connect with the blue-collar voters he failed to attract in the primaries.

"I am thrilled that Joe Biden will be my vice president. The conversations we've been having over the past couple of days make me absolutely convinced he is the right man for the job," Obama told reporters in Eau Claire, Wisconsin.

"He's got the passion to lift up middle-class Americans. He hasn't forgotten his working class roots," Obama said.

Obama said he was "tooling around with my speech a little bit" and tried to lower expectations.

"It may not be as good as the other headliners the first three nights but hopefully it will make clear the choice the American people are going to face in November," he said.

(Additional reporting by Caren Bohan, Andrea Hopkins and Keith Coffman; Editing by David Wiessler)