Joe Biden: Will he take on Hillary Clinton or not?

The qualities that make US Vice-President Joseph Biden good at foreign policy - looking at facts in granular detail, weighing options - make him a lousy presidential candidate. Case in point: he still hasn't even decided whether he's running for president.

In Washington people talk about the Biden Hour. The vice-president likes to talk, and so schedules are adjusted accordingly.

Lately people have been waiting to hear whether or not he'll run for president.

Given the stakes - a job that's arguably the most powerful one in the world - it's worth looking at his approach towards the campaign. His strategy reveals quirks of his personality as well as ways in which he helps to formulate the president's global strategy.

As a candidate, Biden would bring a wealth of foreign-policy experience. He served as the chairman of the US senate foreign relations committee and is now President Barack Obama's adviser on world affairs.

Biden is conservative in his approach to these issues. He's argued for a smaller military role for the US, advocating a targeted approach with drones and special forces rather than the large deployment of troops. His foreign policy is minimalist and comparatively risk averse for the American military.

Like his foreign policy, Biden's strategy for a presidential campaign has been carefully thought-out and cautious. It's has also been his un-doing, at least as a candidate.

Pundits say the window for Biden to decide is closing rapidly. Even if he wanted to run, he wouldn't stand a chance against the leading Democratic candidate, Hillary Clinton, especially after her noteworthy performance in a debate on Tuesday.

But Politico has reported, external it could be another few days before Biden decides if he's in or out of the presidential race - despite reports since August that he was considering a run.

But as both Biden and his confidant, President Obama know, inaction is also a form of action. That's true in foreign policy as well as in campaigns.

When it comes to the race, Biden has done virtually nothing. Yet he plays such a prominent role in foreign policy and presidential decision-making that he's has had an impact, even as a non-candidate.

Clinton used to support Obama's trade deal, the Trans-Pacific Partnership, calling it "the gold standard in trade agreements". But now she doesn't, according to Ryan Lizza, external, partly to differentiate herself from a Candidate Biden, who supports the deal.

Her new position could help her win over labour leaders and others who don't like the trade deal.

On Wednesday morning about a dozen photographers and reporters gathered outside the White House - an unusual number for an event on "infrastructure projects" in the US. They wanted to see if the keynote speaker would say something about the campaign - maybe after he talked about railways and seaports.

Biden arrived late to the event in a room on the third floor in the Eisenhower Executive Office Building. He was in good spirits.

Dressed in a crisp white shirt and blue jacket, he sat at a wooden table and looked around at administration officials, high-speed rail executives and others.

One of the guests, Jeff Zients, the director of the National Economic Council at the White House, looked at Biden and said: "We are very lucky to have you here."

Many others in Washington, whether Democrat or Republican, would agree. "There's a lot of respect for Biden," said Juan Zarate, who served as a senior counterterrorism official under President George W Bush.

Biden's 42 years in Washington has earned him admirers and allies on both sides of the aisle, says Suzanne Nossel, a former deputy assistant secretary of state under Obama. "His career has a very long arc."

But he's also managed to avoid being labelled a predictable Washington insider. "Anytime you're in the room with him, it's not as if you know exactly what he's going to say," she says.

At the transportation panel, Biden looked around the table. "The good news for you guys is I have a luncheon date with a guy I can't say no to," he said. "Hopefully he'll be running late."

Every week Biden has lunch with the president, talking about the world and personal matters too. The meals last an hour or so. But for Biden the deliberative process - thinking an issue over before making a decision and advising the president - requires more.

"He does take a long time to think it through," said Leslie Gelb, president emeritus of the Council on Foreign Relations. "And all of a sudden it pops out."

This seems to be the way he's approaching a presidential bid. After finishing his remarks, Biden picked up a black folder and headed for the door. Then he turned around, looking at the journalists in the room.

Bloomberg's Margaret Talev called out, "operatically", she said later, to ask what he thought of the Democratic debate - and whether he'd run.

Biden was quiet.

At 72, he has a gravelly voice and looks pale and preoccupied - and sometimes hesitant. Another candidate, and perhaps the next president, could plunge ahead with things - whether answering reporters' questions or wading into the world's problems.

The results may be good or bad, depending upon your view of the candidate and of the US role in the world. Right now, though, only one man knows whether he'll take a more active part in shaping the campaign.

He answered the first question, which was about the Democratic debate, saying he thought "every one of those folks", the ones on stage, "did well".

Then he said, "Thanks," and walked out the door.

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