DENVER, Colorado (CNN) -- Former President Bill Clinton declared Barack Obama "ready to be president of the United States" at the Democratic National Convention Wednesday, after months of attacks from Hillary Clinton supporters on the Democratic nominee's lack of experience.

Bill Clinton himself was among the most outspoken proponents of that line of criticism of Obama.

But Wednesday, Clinton reversed himself, pointing out that Republicans had used the same line of attack against him when he first ran for president.

"It didn't work in 1992, because we were on the right side of history," Clinton said. "And it won't work in 2008, because Barack Obama is on the right side of history."

Obama made history a few hours before Clinton's speech, becoming the first African-American to be nominated for president by a major party. Hillary Clinton interrupted a roll call vote to ask that he be nominated by acclamation, a carefully choreographed maneuver designed to unite the party after the bitter primary battle between Obama and Clinton. Watch Clinton say why he thinks Obama is ready to lead »

Bill Clinton continued that theme in his speech.

"Last night, Hillary told us in no uncertain terms that she is going to do everything in her power to elect Barack Obama," Clinton said of his wife, who ran against Obama for the Democratic nomination and urged her backers Tuesday night to support him. Watch the entire speech »

"That makes two of us -- actually that makes 18 million of us," he said, a reference to the number of Democratic primary voters who backed Hillary Clinton.

Bill Clinton received a rapturous welcome when he appeared on stage to the tune of "Don't Stop Thinking About Tomorrow," his 1992 campaign theme song.

He soaked up the applause for several minutes, repeatedly thanking the crowd and finally saying firmly, but with a laugh, "Sit down!"

He attacked John McCain, the Republican candidate, as someone who would continue the failed policies of the Bush administration: "More tax cuts for the wealthiest Americans that will swell the deficit, increase inequality, and weaken the economy. More Band-Aids for health care that will enrich insurance companies, impoverish families and increase the number of uninsured. More going it alone in the world, instead of building the shared responsibilities and shared opportunities necessary to advance our security and restore our influence." iReport.com: React to convention speeches

But Obama, he said, "will lead us away from the division and fear of the last eight years and back to hope."

He closed with an echo of his 1992 portrayal of himself as the Man from Hope, his hometown in Arkansas.

"And so if you, like me, believe that America must always be a place called Hope, then join Hillary and Chelsea and me in making Barack Obama the next president of the United States."

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