Rare is the senator who hasn’t praised Vice President Joseph R. Biden Jr.’s character.

But how do the senators who served with him reflect on Biden as a politician, and how do they feel he would perform as a commander in chief?

“He has sufficient independence of thought and sufficient energy to be a very strong leader,” former Indiana GOP Sen. Richard G. Lugar told CQ Roll Call this week, as Biden considers another run for the Oval Office.

A Quinnipiac University poll released Thursday showed Biden performing stronger than Hillary Rodham Clinton in matchups against the leading GOP candidates.

Lugar evoked the consensus view from former and current senators of both parties, even those publicly backing Clinton, that Biden’s attributes in the Senate — his congeniality, his foreign policy chops, and yes, that signature outspokenness — would strengthen his candidacy should he decide to run.

With the exception of Delaware Sen. Thomas R. Carper, who hasn’t yet backed a candidate in the Democratic primary (“What’s the name of that play, ‘Waiting for Godot?’ In this case it’s waiting for Joe,” he told CQ Roll Call on Wednesday.), those currently in the Senate did not return request for comment about the vice president. Former senators were more willing to speak about Biden.

While the attention is on Biden’s presidential deliberations, it’s easy to lose sight of just how long he served in the Senate — he had already been there for 15 years by the time of his first presidential campaign nearly 30 years ago.

“Even in 1988, he was considered a veteran,” said former Nevada Sen. Richard Bryan, a Democrat who served from 1989 to 2001.

Lugar served with Biden on the Foreign Relations Committee, where he honed the expertise that arguably influenced his selection as vice president.

“I was always impressed with the fact that he had the courage of his convictions,” Lugar said. “He was prepared to speak out during hearings and public gatherings, [and] stated strong opinions that might have been controversial within the Democratic party.”

He recalled Biden taking a stand on the future of Iraq when he proposed in 2006 the country be divided into three autonomous regions dominated by the Shiites, Sunnis and Kurds.

A commander in chief, Lugar added, “really does have to have a comprehensive grasp of foreign policy,” and different countries. “I think that Joe Biden fits that standard very admirably.”

Aside from chairing the Foreign Relations Committee, he presided over the Judiciary Committee during what Republican former Wyoming Sen. Alan Simpson called “the real tough ones” — namely the contentious confirmation hearings of Robert Bork and now-Supreme Court Justice Clarence Thomas.

“From day one, it was just a public dumping on my friend,” former Missouri Republican Sen. Jack Danforth, who served from 1976 to 1995, said of the treatment Thomas received.

But Danforth didn’t blame Biden. “I think he was trying his best to be fair,” he said.

“He tries to work with all kinds of people whether they agree with him or not,” Danforth continued. “I think that’s a very good thing in a politician and really what’s missing in today’s politics — but not for lack of Joe’s trying .”

The longevity of Biden’s public service has shaped his approach to politics, his former colleagues agreed.

“He’s kind of old school. I mean that in a positive way,” said Democratic former Indiana Sen. Evan Bayh, who served from 1999 to 2011.

Bayh has officially backed Clinton, but three generations of his family have worked with Biden. Before Bayh himself started running into Biden in the Senate gym, Bayh’s father served with Biden in the Senate. Bayh’s son, Beau, interned for the vice president this summer.

“Joe was kind of a bridge between a previous generation in which senators were close personally — and that mattered more than party and ideology — and today’s Senate, which is much more partisan,” Bayh added.

But the Biden his former colleagues know wouldn’t have been who he is had he not also harbored clear presidential ambitions.

“He always felt he was capable of becoming president,” said a former longtime Democratic senator who requested anonymity because he didn’t want to come between Biden and Clinton.

Becoming vice president “was kind of nirvana for him,” the former senator said. “He was just outwardly gleeful about what had visited him.”

It’s hardly uncommon for senators to run for president, Bayh said, pointing to his own past interest in seeking the White House. “Not too many people get elected to the U.S. Senate if you suffer from low esteem,” he said.

But Democratic former North Dakota Sen. Byron Dorgan, who, like Bayh, served in the Senate before and after Biden assumed the vice presidency, recalled of Biden, “He still wanted us to call him Joe.”

Now contemplating a third run for president, Biden is 72. CNN political commentator Carl Bernstein said earlier this month that he’s heard Biden might pledge to serve only one term should he decide to run.

Those who know him don’t see age as an issue.

“Some people may question, is age a handicap?” Republican former Georgia Sen. Saxby Chambliss said. “I’m not sure it is. I look at his activities, his energy level is obviously pretty high.”

Carper agreed. “He may be the youngest 72-year-old guy around.”

The biggest caveat that came up over and over again when discussing Biden’s strengths as a senator and as a past and potential future presidential candidate? He talks — a lot.

“He can be a great speaker for the first 20 minutes or so,” said the longtime Democratic senator who wished not to be identified. “He doesn’t read his audiences very well, never has.”

But most former members CQ Roll Call spoke with, from both parties, agreed that Biden’s penchant for speaking his mind, long seen as his greatest vulnerability, could actually enhance his appeal on the campaign trail, and possibly even help him overcome other vulnerabilities, like his age or a late entrance into the race.

“Joe says what’s on his mind. [Donald] Trump says what’s on his mind, and it’s been an advantage for him,” Chambliss said.

Bayh suggested that Biden’s off-the-cuff remarks have grown more “endearing” over time, while his authenticity, especially in the face of family tragedy, could resonate with voters.

“It’s a little bit of the attraction some people found in Robert Kennedy, when his brother had been assassinated,” Bayh said recalling the pain and anguish the former attorney general and New York senator displayed.

“He threw himself into the presidential campaign, and people related to his vulnerability and knew that his suffering had been real, and perhaps it gave him better insight into their struggles.”

On a Wednesday conference call with members of the Democratic National Committee about the Iran deal, Biden said he and his family are evaluating “whether or not there is the emotional fuel at this time to run,” CNN reported.

Biden’s love of his family is something Carper, a personal friend, knows well.

“I think one of the things that might hurt him,” Carper said, is that if he runs, “there will be some times when he’ll skip an event just so that he can be at home.”

But that doesn’t concern Delaware’s senior senator.

By virtue of having run before and having served in the White House as number two, Biden would have an advantage, Carper argued.

“He’s campaigned for hundreds of congressional, gubernatorial and senate races as vice president in the last six and half years, and picked up a lot of IOUs,” Carper said.

Republicans agree.

“ Politics has been his life. He knows how the game is played,” Chambliss echoed. “He would be prepared to assume the role, because he’s been there.”

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