Newly-nominated Democratic vice presidential candidate Joe Biden on Wednesday counted on his long resume of foreign policy experience to slam the Bush administration and link Republican presidential candidate John McCain to an entrenched Iraq war policy.

Attending the Democratic National Convention to claim his No. 2 spot on the ticket, Biden was joined at the end of his speech by presidential nominee Barack Obama -- but not before Biden did Obama's bidding, faulting the administration for losing the nation's prominence in the world and saying a McCain presidency would be four more years of the same.

"Our country is less secure and more isolated than at any time in recent history," Biden said. "The Bush-McCain foreign policy has dug us into a very deep hole, with very few friends to help us climb out."

Biden, who has a penchant for verbal gaffes, made a slip of his own but one that earned wild laughter as Biden mistook President Bush for McCain.

"You know, folks, that's the America that George Bush has left us. And that's the America we'll continue to get if George -- excuse me, if John McCain is elected president of the United States of America. Freudian slip.  Freudian slip," he said.

The Delaware senator took the stage after accepting his party's nomination by acclamation. The process capped a dramatic day in which Obama's vanquished rival, Hillary Clinton, took to the floor of the convention center to put an end to the roll call vote and move for Obama to be nominated by acclamation. That was followed up by a rousing speech delivered by former President Clinton, who forcefully offered his and his wife's support for the Democratic team.

"I want everybody to now understand why I am so proud to have Joe Biden and Jill Biden and Beau Biden and Mama Biden and the whole Biden family with me on this journey to take America back," Obama said after Biden's speech.

Biden drew sharp contrasts between his new boss, whom he will start campaigning with on Friday in the swing states of Pennsylvania, Ohio and Michigan, and his old friend McCain.

"The choice in this election is clear. These times require more than a good soldier," he said, referring to McCain's military service that includes his legendary five and half years as a prisoner of war in Vietnam. "They require a wise leader who can deliver change. The change everybody knows we need. Barack Obama will deliver that change."

Known for his verbosity, Biden has a blunt speaking style that contrasts with Obama's careful nuance. His role will surely involve playing the attack dog, a position usually reserved for vice-presidential nominees.

Biden already took on that role in his acceptance speech, casting doubt on McCain's judgment, noting the Republican shared Bush's preference for staying in Iraq, not setting time lines for troops to withdraw, not giving more attention to Afghanistan and not holding talks with Iran.

Over and over, he said Obama had been proven correct.

"Again and again, on the most important national security issues of our time, John McCain was wrong, and Barack Obama was proven right."

Biden spoke glowingly of McCain's military service but cited his political record over the last few years to paint him as a Bush clone, whipping the crowd into a frenzied chant of "That's not change; that's more of the same."

Biden's acceptance speech marks a high point in his 30-plus year political career that includes two failed bids for the White House. Biden's career appeared to be heading back into obscurity after he dropped out of this year's race

Biden's son, Beau Biden, a Navy Reservist who is scheduled to go to Iraq Oct. 3 for a year-long deployment, introduced his father in an emotional speech in which he noted how Biden, who commutes daily to Washington, D.C., from his home in Delaware, always made time for his family.

Beau Biden, 39, is Delaware's state attorney general and apparent heir to his father's Senate seat if Democrats win the White House in November.

In his remarks, the younger Biden alluded to his imminent military service when he said because of other duties he won't be able to stand by his father in the fall the way his father has for his family.

"So I have something to ask of you," he said. "Be there for my dad like he was for me.  Be there for Barack Obama because our country needs him. ... Be there because Barack and Obama and Joe Biden will deliver America the change we so desperately need."

In Biden, Obama chose a foreign policy heavyweight who has a biography as compelling as his own.

Elected to the Senate at the age of 29 in 1972, Biden confronted a personal tragedy before he could take office. His wife and their 13-month-old daughter, Naomi, were killed when a tractor-trailer broad-sided her station wagon. His two sons survived the crash, and Biden took his oath of office for his first term at the hospital bedside his sons. Biden later remarried and had a daughter with his second wife.

A Catholic with blue-collar roots, Biden, 65, is expected to appeal to working-class white voters that Obama struggled to pick off from Clinton during the primary season.

In his brief appearance on stage on Wednesday night, Obama noted that the team's effort to appeal to the masses with its move from Pepsi Center to Invesco Field at Mile High is aimed at reaching the widest audience of middle America.

"At the start of this campaign we had a very simple idea, which is change in America doesn't start from the top down. It starts from the bottom up. That change is brought about because ordinary people do extraordinary things," Obama said. "So we want to open up this convention to make sure that everybody who wants to come and join in the party and join in the effort to take America back, I think we are going to have a great night tomorrow night and I look forward to seeing you there."

But Biden's bluntness could also be one of his weaknesses. He has made a number of gaffes over the years. During the primary, Biden called Obama "articulate " and "clean,"  which some found  to be racially insensitive.

He also had to clarify a recent remark in which he said, "You cannot go to a 7-Eleven or a Dunkin' Donuts unless you have a slight Indian accent."

The Obama campaign is betting that Biden's background and good intentions will overshadow his stumbles.

No sooner had word spread of Obama's selection than McCain's campaign unleashed its first of many attacks, citing Biden's earlier statements criticizing Obama for his lack of experience. Biden said last year that Obama was not ready to serve as president, a position that was reversed on Wednesday by both the vice presidential nominee and Bill Clinton.