WASHINGTON — The selection of a vice presidential running mate has been one of the most clandestine operations in modern American politics. Then along came Joe Biden.

The apparent Democratic presidential nominee has made many of the moves others in his position have avoided in the past. He has: narrowed the field substantially in a nationally televised debate by pledging to pick a woman running mate; talked about the process in great detail at his now-virtual fundraisers; interviewed one likely candidate on his own podcast; and routinely offers typically candid updates in TV interviews.

A former two-term vice president himself, Biden has also answered more voters’ questions about the other half of his ticket on the campaign trail than any other Democratic hopeful in recent memory, often going so far as to name some likely candidates.

“The one thing I know a lot about is the vice presidency,” Biden often jokes when the subject comes up.

And it’s clear, based on the substantial body of his own public comments, that his experience as President Barack Obama’s second in command shapes his thinking as he approaches the task.

Put simply, Biden appears to be looking for his own Biden, especially now in a moment of a public health crisis.

He’s made clear that he is going to need his vice president to be someone who can manage significant tasks, as he did especially in the early days of the Obama administration, which inherited the Great Recession and ongoing wars in Iraq and Afghanistan, while pursuing a significant policy agenda that included health care reform.

Biden is now describing the job he faces if inaugurated in January as even more daunting than what Obama did, with a new economic crisis prompted by the global health crisis due to the coronavirus pandemic.

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“No president has the capacity in the 21st century to handle everything. You've got to be able to, not a joke, turn over presidential responsibility. And you can't do it for a Cabinet member because internationally it is not taken as seriously,” he said in January.

Based on conversations with multiple Biden advisers, allies and other influential Democrats, the former vice president has not tipped his hand about any specific individual. One top Biden adviser said that, while he might in his own mind have a favorite or two at this stage, he has been clear that he wants a thorough vetting and deliberative process to run its course.

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Some speculate that the twin health and economic crises could bolster the case for candidates on his short list like Massachusetts Sen. Elizabeth Warren, or to a lesser extent Minnesota Sen. Amy Klobuchar, who have Washington experience and demonstrated in the course of the Democratic primaries a fluency in the kinds of issues Biden would confront.

Warren, who is expected to endorse Biden in the coming days, has spoken with him multiple times since she ended her campaign, primarily about policy as he has moved in a more progressive direction on issues such as student debt and bankruptcy, flatly endorsing her plan on the latter. Klobuchar held multiple surrogate events for Biden in the brief window between when she ended her candidacy and public campaigning ceased because of the pandemic.

California Sen. Kamala Harris last week joined Biden for a virtual fundraiser. “You ran a hell of a race,” Biden said. “The biggest thing we can do is make Donald Trump a one-term president. So I'm coming for you, kid.”

Another potential finalist, Michigan Gov. Gretchen Whitmer, whom Biden interviewed for his new audio series, “Here’s the Deal,” is gaining notice as well. “Governor, I've paid close attention to your leadership in Michigan from the time you got elected,” Biden noted in the interview.

But Biden has named or alluded to another half-dozen Democrats, including former Georgia House Democratic Leader Stacey Abrams, New Hampshire Sens. Jeanne Shaheen and Maggie Hassan, and former Deputy U.S. Attorney General Sally Yates, as being capable of serving in the office.

“He truly hasn’t narrowed down his thinking on this,” one top Biden adviser told NBC. “He genuinely intends to go through this process,” the adviser added, while noting he ultimately will “go with his gut. That’s who he is and how he operates.”

By month’s end, Biden will formally announce the team to oversee that process, expected to include his campaign's top lawyers, general counsel Dana Remus and Bob Bauer; national campaign co-chairman Cedric Richmond; and either formally or informally a number of longtime advisers, including Ron Klain, his first chief of staff as vice president.

While that signals the start of an official review, Biden and that kitchen cabinet of longtime aides and current campaign staff have been discussing the vice presidency since before he launched his candidacy.

During the campaign, Biden also couldn’t help but size up some Democratic primary rivals as potential running mates — as Obama did of him during the 2008 campaign.

And now, with active campaigning on hold due to the coronavirus pandemic, Biden has been sounding out a larger universe of Democrats to gauge their reactions to some possibilities.

Those familiar with Biden’s decision-making process say he’ll sometimes cater the discussion to the individual he’s talking to; as one aide put it recently, he probably will have a different “short list” for every person he speaks with.

The unusual break in campaigning gives Biden more space to make a decision and time to conduct a vetting process than he might otherwise have had. He’s discussed it with Obama and sought counsel from those who ran his process in 2008 — the one that of course ended with Biden himself on the ticket.

Biden told donors last week that Obama’s advice was in part to look for someone who has experience where he is lacking, a dynamic that had served him well.

When Biden has discussed what he’s looking for in a running mate, it’s almost exclusively been through the prism of what kind of partner that person would be in the White House — an important signal that short-term political considerations are secondary to governing ones.

“The data, the history are pretty clear that [the election] is about two people at the top of the ticket. So politically I think 95 percent of this is, just don't make a mistake,” David Plouffe, Obama’s campaign manager in 2008, said. “I think the most important factors to them will be, one, is it somebody everybody says can take over [as president] on day one. By definition, that would be somebody who can handle the crisis in the aftermath. And secondly, somebody who Biden really believes could be operationally excellent.”

Twelve years ago, Obama’s vetting team did not hold a first formal meeting until June. Plouffe noted that the team’s role is about providing a full picture of the strengths, weaknesses and background of a potential pick to inform the nominee’s final choices. As Biden put it recently, the team will ensure “there’s not going to be any snafu” with any final pick.

While Obama had to conduct in-person interviews with potential candidates in the heat of a campaign, Biden appears to have weeks ahead of him where he could have intimate conversations, either in person or through videoconferencing, without the same need for obsessive secrecy.

One of Biden’s mantras is that “all politics is personal,” meaning he, even more than most other nominees, is likely to prioritize as a factor in his final decision his personal comfort level and rapport with the choice.

“You have to have somebody who is simpatico with you,” he told voters in New Hampshire in the fall. “I would try to find somebody who number one agreed with me in principle and philosophically where I am, but also someone who in fact could make up for some of my weaknesses, and someone who I can just simply trust.”

“I know the responsibility of a vice president is to always have the president's back. And when they disagree with the president of the United States, do it privately with him because you can't undercut a president,” Biden told donors in Las Vegas in the summer.

But Biden has also been careful to say he’s not looking for a yes-woman.

“I'm not looking for someone to come in and genuflect in the White House,” he told Iowans in January. “You have to be able to be willing to have someone with you who will tell you the truth that they think you're wrong, and not be intimidated by the fact that you're the president sitting behind that desk.”