"The relationship that [Biden] had with Senator Specter was one of the keys to Senator Specter's decision to leave the Republican Party and join the Democratic caucus," Devine said. "There's a lot of trust that was built up between the two of them over the course of decades."
Devine said that it is relationships like this, forged by Biden in his three decades on Capitol Hill, that Obama, with just four years in Washington, now benefits from.
"The Specter decision to join the Democratic Party is the most poignant example of that," he said.
Biden played a key role in the president's decision making process from the time that Justice David Souter announced his retirement, according to White House and Capitol Hill officials. The vice president met with Obama's final four picks for the vacancy and like his boss, was leaning toward Sotomayor.
Administration officials say it was a no-brainer for Biden to be involved in this process. He is a veteran of six Supreme Court confirmation hearings as the chairman of the Senate Judiciary Committee and has more experience on this issue than perhaps any active politician in Washington.
Biden's counsel, Cynthia Hogan, leads the team that will guide Sotomayor through the confirmation process, and Ron Klain, Biden's chief of staff and former chief counsel to the Senate Judiciary Committee, also plays an integral role.
Biden enjoys wide access to his boss. They share a weekly private lunch and he is included in the president's meetings with Secretary of State Hillary Clinton and Secretary of Defense Robert Gates.
"When he needs to see him, he sees him," an administration official said.
They haven't always seen eye-to-eye on tactical decisions, but administration officials say the president and vice president have not had major disagreements on key policy issues.
But some political strategists say that it is exactly that quality that not only makes Biden Biden but also makes him a strong partner.
"The valor of that candor to the president... vastly outweighs any occasional problem caused by him being too candid or blunt or impolitic with his remarks," an administration official said.
Sometimes that penchant for speaking his mind is exactly what gets Biden into trouble, like when he seemed to ratchet up the panic during the swine flu outbreak, just as Obama was urging calm.
"I would tell members of my family -- and I have -- I wouldn't go anywhere in confined places now. It's not that it's going to Mexico in a confined aircraft where one person sneezes, that goes all the way through the aircraft," Biden said on April 30.
The White House had to quickly backtrack and clarify the vice president's remarks.
"I understand what he said, and I'm telling you what he meant to say," press secretary Robert Gibbs said. "Obviously, if anybody was unduly alarmed for whatever reason, we would apologize for that. And I hope that my remarks and the remarks of people at the CDC and Secretary Napolitano have appropriately cleared up what he meant to say."
White House officials admit that the vice president's statement was "less than ideal" and "caused heartburn" but do not think it made a noticeable dent in Biden's image and standing.