At a rally Saturday in Springfield, Ill., Sen. Obama said he searched for a running mate who could step in and be president.
"Joe Biden is that rare mix. For decades, he's brought change to Washington, but Washington has not changed him," Obama told the crowd of supporter. "He's an expert on foreign policy whose heart and values are firmly rooted in the middle class. He has stared down dictators and spoken out for American cops and firefighters. He is uniquely suited to be my partner as we work to put our country back on track."
Obama told the crowd that 65-year-old Biden is a statesman who's been tested and proven that he's a leader with a strong moral center.
University of Minnesota political scientist Larry Jacobs says Biden's experience will help balance Obama's weaknesses.
"And the weakness was experience, but he really needed someone like Joe Biden, who had been in Congress and had been a master in the area of foreign policy, to shore up his campaign, even for those Democrats who may not be excited about the Biden-Obama ticket," said Jabobs.
Jacobs says the convention could be the place where those Democrats who are not excited about an Obama-Biden ticket get enthusiastic about it.
"So for the voters out there and the Democrats who are disappointed, I think they are going to get a chance at the convention, where both Bill Clinton and Hillary Clinton will have primetime speeches, to get excited about the Obama-Biden ticket," Jacobs said.
Jacobs says Biden's working class, Catholic roots will also help Obama win white male voters.
National Republican leaders moved quickly to criticize the choice, saying Obama and Biden don't have what it takes to sway voters in swing states like Minnesota.
A recent Minnesota Public Radio-Humphrey Institute poll showed Obama with a 10 point lead in Minnesota. But the poll also found a significant percentage of voters who say they're still undecided.
63-year-old John Hetterick from Plymouth says he thinks Biden brings wisdom to the Obama ticket.
"He does bring the gravitas and experience and age to the table, which, given how much criticism Obama's had for lack of experience, I think it's important that he have that," said Hetterick. "I don't think he's the perfect choice, but I'm not sure there is one out there that would be."
Hetterick considers himself a socially liberal and economically conservative Centrist. He's planning to vote for Obama, because he says he's better than the alternative.
Biden has served in the Senate since 1972. He has played a key role in many major foreign policy matters over the years. Most recently, he has been critical of President Bush's handling of the war in Iraq.
23-year-old Moorhead voter Katherine Staszko says Biden may have a lot of international experience, but he is a bland choice. She says that's why Obama picked him.
"I think he's just playing it safe, because I think if he would have picked another younger, kind of more funky, if you will, candidate, I think that would have really distanced himself with older voters. So, I think it was a pretty safe bet to go with Biden on this one," said Staszko.
Staszko caucused for Hillary Clinton, and says she wishes things could've gone differently in the primaries. But she plans to volunteer to help Obama win in Minnesota.
But not everyone is convinced the Obama-Biden ticket is the best this November.
Voter Glenda Burgeson is one of them. She was hoping Obama would choose Hillary Clinton as a running mate. Now, the lifelong Democrat says she's not sure what she'll do once she gets to the voting booth.
"It's very, very different from just being a Democrat who is pouting, which I obviously am," she said. "My whole mindset has changed, so I don't know what is going to happen between now and November. I must say, I do respect McCain and normally I detest Republican candidates. I respect what he brings and offers, and so I'm just totally open at this point."
Burgeson is just the kind of disenchanted voter that both parties will be trying to win over as we get closer to Election Day.