Democrats Barack Obama and Hillary Clinton joined forces at a carefully staged campaign rally on Friday, promising to bury the grudges from their bruising presidential nominating fight and work together to put Obama in the White House.

The former rivals embraced, lavished praise on each other and vowed to bring the Democratic Party together for the November election fight against Republican John McCain.

"Today we are coming together for the same goal - to elect Barack Obama the next president of the United States," Clinton told the crowd of about 3,000.

"We have gone toe-to-toe in this hard-fought primary, but today and every day going forward we stand shoulder-to-shoulder for the ideals we share and the values we cherish," she said.

The joint appearance in a rural field outside an elementary school in the symbolically named New Hampshire town of Unity was the first time the two shared a stage in public since Obama clinched the Democratic nomination earlier this month.

The Illinois senator has trod cautiously in courting Clinton and her millions of supporters, many still angry about the outcome of their epic 16-month campaign struggle.

"We've made history together," said Obama, who would be the first black U.S. president. Clinton was vying to be the first woman U.S. president. Obama said she had served as an inspiration to millions of women and his own two daughters.

"We shattered barriers that have stood firm since the founding of this nation," he said.

He noted the town of Unity had split its votes evenly during the January 8 New Hampshire primary, with 107 votes for Obama and 107 for Clinton.

"Now we look at them as 214 votes for change in America," Obama said.

FRONT-ROW SEAT

He told reporters earlier this week he hoped the joint appearance in New Hampshire signalled an active role for the New York senator in his White House race.

Clinton, who entered the race in January 2007 a heavy favourite, battled Obama to the end of voting on June 3 in a race that embittered some of her supporters -- particularly some of the women who formed her core constituency.

Whether Obama can win over all of those supporters remains unclear, but many public opinion polls show him solidifying his Democratic backing in recent weeks and moving out to a clear national lead on McCain.

Clinton, who returned to her Senate duties in Washington this week for the first time since dropping out of the Democratic race on June 7, offered strong praise for Obama.

"I've had a front row seat to his candidacy," she said. I've seen his strength and determination, his grace and his grit."

Clinton introduced Obama to her top fundraisers at a private meeting in Washington on Thursday night. Obama already had asked his big donors to help her pay off more than $10 million (5 million pounds) she owes to campaign debtors.

Obama, his wife Michelle, and finance committee chairwoman Penny Pritzker, along with other top Obama donors, each gave Clinton the maximum $2,300 check to help her pay off her debt. Obama will not ask his grass-roots list of 1.5 million donors to kick in on the Clinton debt.

Clinton and her husband, former President Bill Clinton, donated the maximum to Obama's campaign, Clinton aides said.

The two senators flew to Manchester, New Hampshire from Washington together on Obama's campaign plane, sitting in the second row together and chatting amiably for the hour-long flight.

They also shared a bus with a half-dozen aides for the 90-minute ride from Manchester to Unity. Obama spokeswoman Linda Douglass said the bus conversation was light-hearted banter on foods and computers, but the two did adjourn for a private discussion before speaking at the rally.

The tiny town of Unity in New Hampshire, near the Vermont border, was chosen for the rally not only for the obvious symbolism of its name but because the state will be a critical battleground in the race with McCain.

Democrat John Kerry narrowly captured New Hampshire in the 2004 race against Republican President George W. Bush, but Bush beat Democrat Al Gore there in a close race in 2000.