WaPo lead congressional reporter Paul Kane is the world's most insightful political e-mailer. Having exchanged missives with him for more than 15 years now (we worked together long ago in a galaxy far away, at Roll Call), I can vouch for this unquestioned fact. So, from time to time, I like to publish the e-mail exchanges PK and I have. This is one of those times. PK, a son of Philadelphia, graduate of the University of Delaware, Catholic and longtime Senate watcher, knows Joe Biden from head to toe. Below is the conversation we had earlier Monday about Biden's presidential ambitions -- and what, if anything, might come of them. 

FIX: Okay, PK. So, the Biden-might-really-run speculation is in full froth after he and Elizabeth Warren met over the weekend in D.C. I am on the record as being skeptical that there is a path for Biden. I am also on the record as totally clueless as to what is helping him make up his mind. Let’s take the second point first.

What is Joe weighing as he thinks about running? How much is this about making good on the dying wish of his son, Beau, and how much of this is a cold calculation about whether he can win?

PKWhat a campaign season. When things really got going a year or so ago, there was lotsa talk and buzz about one Fightin’ Blue Hen from the University of Delaware and how he would play in the race: Chris Christie, Class of ’84. No one was talking about Biden (UD class of ’65). Now, Biden has managed to actually be driving the conversation in a way that no one saw coming.

Beau’s death has taken on so much significance, on so many levels, it’s hard to overstate. It is both a driving force and a haunting specter. At any given moment, it's the thing that seems to be driving this consideration, but it's also the single biggest factor that argues against a run.

To wit: It’s now widely known that while Beau was in his last months, with cancer again coming after him, he encouraged his father to run for the Democratic nomination. As word of that leaked out, it created the boomlet that we’re currently in. And on top of that, a collection of operatives and donors who are younger and connected to Beau are part of the leading force encouraging the vice president to run.

However, it’s impossible to overstate how devastated the Biden family has been. Biden’s camp has told me that throughout June and July they couldn’t really even schedule the vice president more than a week in advance. Some days he might find out that members of the family were having such tough times grieving that he would have to clear his calendar to tend to the family in his patriarchal duties. While he did rush to the Naval Observatory to meet with Warren, he had previously spent the whole week huddled with family in Wilmington, particularly since it was his last chance to spend time with Beau’s two children before the school year started.

So, given that push and pull, it’s hard to overstate the significance of Beau’s shadow on the race. But it cuts both ways.

All that being said, the decision would probably be a lot easier if Hillary Clinton were clicking on all cylinders and was doing fantastic and didn’t have any hint of scandal about her.

FIX: Right. It seems to me that if we had never heard the phrase “private e-mail server,” the Biden boomlet would had never begun — no matter what Beau Biden wanted. Of course, that didn’t happen. And, here we are. 

As I have read the Biden stories of late, it seems to me that so much of his decision is predicated on where the Clinton e-mail story goes from here. Biden’s path to the nomination, such as it is, looks to me like this: He gets into the race. The e-mail story leads to a complete collapse of Clinton’s campaign. Biden fills the void for Democrats who simply don't think Bernie Sanders can be the party’s nominee come 2016.

Yes, that scenario looks more possible today than it did a month ago. But it still feels like a triple bank shot to me. And does a guy who is the sitting vice president really want to risk the last chapter of his political life on a triple bank shot?  

You know Biden the man way better than me. What do you think the answer is to that question?

PKYes, you’ve pretty much nailed the situation. There’s no disputing that Clinton has floundered at times during this campaign, and that her image among independent/centrist voters has cratered. There’s also no disputing that her standing among core Democratic voters remains very strong. There’s a narrow subset of Democratic voters that do not like Hillary Clinton and have coalesced around Sanders's insurgent bid -- about 30-ish percent of Democrats. But otherwise, she seems in strong standing to win the nomination.

Biden would not enter the race as some sort of icon to those hardcore liberals backing Sanders (and those who had wanted Warren to run). The critique against Clinton – often crystallized in her 2001 vote for bankruptcy legislation strongly opposed by Warren (then a Harvard law professor) applies to Biden, who as a senator took the side of the credit-card industry that employed thousands of Delawareans.

So his path to victory is actually getting into the fight and convincing [Clinton] voters to switch sides.

There are those inside the Biden camp who believe that it's a fight worth getting into -- that once they’re on the same stage together, people will decide they like him a lot more than her.

There are also plenty inside the Biden camp who believe that, given everything he has gone through this year, picking a fight with the Clintons is the last thing he should do -- that, given their well-earned reputation of tough politics, Biden could come away from the race embarrassed [and] more emotionally distraught than previously imagined.

I don't know what the ultimate answer is inside Biden’s own brain. If he gets into the race, he could have made a calculation that, really, after losing his wife and daughter coming into politics 43 years ago, and losing his son at the end of the vice presidency, seriously it can't possibly get worse -- [that] nothing that can happen in challenging the Clintons can be worse than what he’s already experienced.

If so, well, what a wild card he will be. Because, as the old boxing adage goes, the most dangerous fighter is the guy with nothing to lose.

FIX: Holy cow, absolutely.

So, do we have any sense what sort of relationship Biden and Clinton have (if any)? They obviously served together in the Senate and in Obama’s Cabinet. They also ran against each other in 2008 — although Biden was never a real threat to her in that race. 

PK: In terms of Biden-Clinton, I think the bulk of their personal relationship was actually formed during Obama's first term and not in the Senate, where they were on different tracks most of the time even though they served together for eight years. He was the ranking member or chairman of the Foreign Relations Committee, while she was serving on the Armed Services Committee. The way the Senate works, in terms of your morning schedule and often your overseas [congressional delegation] trips, it's very often based on the committees you serve on. So that Chairman Biden became close to a young senator from Illinois who served on Foreign Relations, Barack Obama, while veterans on the Armed Services Committee – including John McCain and Carl Levin – ended up closer to Hillary Clinton.

It’s not a Jets-vs.-Sharks situation; it's just different orbits.

In Obama’s first term, however, you saw some level of rivalry pop up between the vice president and secretary of state as the big decisions of diplomacy and national security were being made. Clinton often took a slightly more hawkish position and seemed to align herself more often than not with Bob Gates, the Republican-appointed secretary of defense who served the first few years of Obama’s term. Biden, for example, pushed a more modest footprint. Clinton joined Gates in pushing for a robust surge of troops into Afghanistan in 2009. She urged a more aggressive use of force in Syria.

Their most famous split was on the May 2011 raid in Pakistan that killed Osama bin Laden. Clinton says that she joined with then-CIA Director Leon Panetta as forceful advocates for the raid, and Biden has openly admitted that he advised the mission was too risky.

Of course, potentially in a sign of things to come, there’s a dispute over Clinton's own view of how strongly she encouraged the mission. In October 2013, during a paid speech in Atlanta, she subtly criticized Biden for opposing the missionHowever, in Biden’s own recounting of the decision-making process, laid out in a speech to congressional Democrats three years ago, only Panetta was truly hawkish on the raid, which if you read this closely, is a not-so-subtle jab Clinton"Every single person in that room hedged their bet except Leon Panetta. Leon said go. Everyone else said, 49, 51.”

So, you know, maybe those two shots, fired years ago, were the beginning of the primary.

FIXI also think Biden — probably rightly — views himself as more of a bold risk-taker than Clinton. On gay marriage, for example, Biden was out front of both Clinton and Obama in pushing to recognize same-sex marriageMy guess is his old-school 'I say what I mean and I mean what I say' approach to politics means that he finds her cautious-to-a-fault style super annoying. 

Okay, enough pop psychology. Does he run or not? And, in one sentence, why or why not?

PK: I can’t answer the question. No one really can except Biden himself. I do know that in June 2003, two really smart young reporters at Roll Call wrote a story with this headline: "Biden Aides Plot Strategy; Senator Sheds '88 Approach."

Do you know who those young reporters were? Paul Kane and Chris Cillizza. Biden was considering back then -- as John Kerry floundered and unelectable Howard Dean surged -- jumping into the race very late. What he had already decided way back then was that he never wanted to run a big, bloated frontrunner campaign ever again, not after his aborted effort in 1988. He wanted it to be lean; he almost preferred being the underdog.

"If I run, I don't need anybody to tell me what my message is," he told me back then.

He decided against the bid, in part because he was much younger then (60) and knew there were a couple more chances at running. Now, however, time has run out. He’s 72; he’d be 74 on Inauguration Day 2017.

Bringing it back to Beau: One of the most difficult parts of this decision, I’m told, is that a year ago, when Beau seemed healthy and destined to become Delaware’s governor and possibly run for president someday, the idea of Joe Biden stepping out of the electoral spotlight was easier. He would become an elder statesmen and bask in the glow of Beau’s rising star. Now that shining light has been taken from him, and there’s no time left for his own career. It’s now or never.

I asked him in June 2003 whether it was already too late. “I don’t know,” he said. “All the smart money says it is.”

Back then he opted against it. Now, I’m beginning to think he’s decided that – after everything he’s already been through, so much tragedy – he has nothing left to lose.