WRAPUP 11-Clinton delivers ringing call for Democratic unity

* Clinton links McCain with Bush

* Former President Clinton tears up at her speech

* Former Virginia Gov. Warner delivers keynote speech

By John Whitesides, Political Correspondent

DENVER, Aug 26 (Reuters) - Hillary Clinton delivered a ringing call for Democratic Party unity on Tuesday, promising to work for Barack Obama and challenging her supporters to bury their grudges and rally behind his White House bid.

"Whether you voted for me or voted for Barack, the time is now to unite as a single party with a single purpose," said Clinton in a speech Democrats hope will end a lingering party rift left over from their bitter nominating fight.

Clinton, a New York senator, praised Obama and said Democrats could not sit on the sidelines and watch Republican presidential candidate John McCain take the White House and "squander the promise of our country."

"No way, no how, no McCain. Barack Obama is my candidate and he must be our president," Clinton told a roaring crowd waving a sea of white "Hillary" signs.

Clinton used her highly anticipated turn in the spotlight to say Democrats must unite to help the first-term Illinois senator beat McCain in the Nov. 4 election. A Democrat is needed in the White House to turn around the struggling U.S. economy, she said.

"When Barack Obama is in the White House, he'll revitalize our economy, defend the working people of America, and meet the global challenges of our time," Clinton said.

Her husband, former President Bill Clinton, watched from the balcony. At one point his eyes welled with tears and he mouthed the words "I love you."

Obama watched the speech on television in Billings, Montana, as he makes his way to Denver to accept the nomination on Thursday night. "That was a strong speech," he said. "I thought she was outstanding."

He called Hillary and Bill Clinton afterward to congratulate them on the speech and tell them he was grateful for their support, Obama adviser Robert Gibbs said.

Clinton also offered plenty of criticism of McCain, an Arizona senator who she called "my colleague and my friend."

"But we don't need four more years of the last eight years," she said, linking McCain to the policies of Republican President George W. Bush.

"John McCain says the economy is fundamentally sound. John McCain doesn't think that 47 million people without health insurance is a crisis. John McCain wants to privatize Social Security. And in 2008, he still thinks it's okay when women don't earn equal pay for equal work," Clinton said.