Democratic vice presidential nominee Sen. Joseph Biden (Del.) delivered an acceptance speech Wednesday night that won applause as he sought to link presumptive GOP presidential nominee Sen. John McCain (Ariz.) to President Bush. However, the biggest roar of the evening came when Democratic presidential nominee Sen. Barack Obama (Ill.) joined Biden on stage for a surprise appearance.

“I want everybody to now understand why I am so proud to have Joe Biden and Jill Biden and Beau Biden and Mama Biden on this journey to take America back,” Obama said in what appeared to be unscripted remarks that referenced Biden’s wife, son and mother.

“I think the convention’s gone pretty well so far. What do you think?” Obama said. “If I’m not mistaken, Hillary Clinton rocked the house last night.”

Obama told delegates that Thursday’s speech at Invesco Field would be “to make sure everybody who wants to come can join in the party. And I look forward to seeing you there.”

Obama’s arrival overshadowed a sometimes uneven performance by Biden, who frequently went off-script and repeatedly stumbled over his own speech – qualities that have made some Democrats nervous about his ability to stay on message on the campaign trail this fall. Still, the minor gaffes did not prevent the crowd from loudly cheering a few of the zingers he delivered.

In one memorable moment, Biden attempted to compare President Bush to McCain, but he went a bit further than he had intended.

After going through a litany of economic ills that he blamed on Bush, Biden said, “That’s the America that George Bush has left us, and that’s the future that George, excuse me, John McCain will give us. Freudian slip.”

In his speech, Biden attempted to introduce himself to the nation, attack McCain’s foreign policy credentials, and promote Obama’s readiness for the White House and his policy proposals.

Biden told delegates that his blue-collar roots and strong family had made him a fighter.

“When I got knocked down by guys bigger than me, [my mother], and this is the God’s truth, she sent me back out and demanded that I bloody their nose so I could walk down the street the next day,” Biden said. “And that’s what I did.”

He added, “I’ve never seen a time when Washington has watched so many people get knocked down without doing anything to help them get back up.”

Biden also highlighted both Obama’s domestic and foreign policy agendas, saying an Obama administration would lower taxes for 95 percent of workers, increase alternative energy options, bring down health care costs, and refashion American foreign policy to confront terrorism threats in Afghanistan and Pakistan.

Along the way, Biden attempted to point out what he said were McCain’s flawed foreign policy decisions. For example, Biden said, “Should we trust John McCain’s judgment when he says we can’t have no timelines to draw down our troops from Iraq – that we must stay indefinitely? Or should we listen to Barack Obama, who says shift responsibility to the Iraqis and set a time to bring our combat troops home? John McCain was wrong. Barack Obama was right.”