President Obama and Vice President Joe BidenJoe Biden2020 Dems slam Trump decision on West Bank settlements Trump calls latest impeachment hearings 'a great day for Republicans' Overnight Health Care: GOP senator says drug price action unlikely this year | House panel weighs ban on flavored e-cigs | New York sues Juul MORE on Friday appeared at their first joint campaign rally this year on behalf Delaware nominee Chris CoonsChristopher (Chris) Andrew CoonsSenators press Facebook over user location tracking policies Senators introduce bipartisan bill restricting police use of facial recognition tech Centrist Democrats seize on state election wins to rail against Warren's agenda MORE (D), lauding him and one another after two years in office.

The president and vice president presented a unified front for the audience in Biden's hometown of Wilmington and made the case that Coons's election is crucial to keeping their agenda moving forward.

"This guy has a backbone like a ramrod," Biden said while introducing Obama, adding that he has "a brain bigger than his skull and a heart to match both."

Obama took the stage to a hardy ovation from the crowd and said, "I've had to make a lot of decisions over the last 24 months ...The single best decision I have made was selecting Joe Biden as my running mate."

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The president's comment happened to come after the White House dismissed speculation last week that Secretary of State Hillary ClintonHillary Diane Rodham ClintonDemocrats ask judge for quick ruling on McGahn subpoena Hillary Clinton: 'Every day Stephen Miller remains in the White House is an emergency' The Memo: Centrists change tone of Democratic race MORE, who ran against Obama in the 2008 Democratic presidential primary, could join his 2012 reelection campaign as his running mate.

Obama and Biden made the case for electing Coons to the Senate, saying it will help them continue to revive the economy in the two years between this election and the next.

"It's really important we keep this momentum going, and it's impossible to keep this momentum going without the United States Senate," Biden said. "When Chris Coons goes to the United States Senate, you will never, ever, ever wonder why you voted for him."

Obama urged Democrats to work hard to elect Coons, even though most polls show him leading his Republican opponent Christine O'Donnell by double digits.

"It is difficult here, and it is difficult across the nation," Obama said "I don't want anyone here taking this for granted. This is a tough political environment."

Obama and Biden did not make mention of O'Donnell, who has nearly single-handedly helped attract national attention to the race. O'Donnell shocked many by defeating nine-term centrist Rep. Mike Castle (R) in the GOP Senate primary, then raised questions about her personal background by making controversial statements about religion and sexuality.

Obama, however, did aim at Republicans, saying they opposed his agenda for pure political gain and would impede progress by instituting policies that failed in the past.

"You have to give them credit, in terms of short-term tactics it wasn't a bad strategy," he said. "In terms of what's good for the country it, uh, didn't work out so well."

Biden appeared to be within his element during his third appearance on behalf of Coons, who is running for his old Senate seat. 

The vice president noted that Obama loves to talk about his home state of Hawaii and his adopted hometown of Chicago, but said, "He would not be president of the United States today but for Delaware," noting that two of his top campaign advisers, Dan Pfeiffer and David Plouffe, hail from the First State.

"Dan Pfeiffer's mom and dad, we owe you big," Biden added.