What Joe Biden Tells Top Democrats When He Thinks No Reporters Are Listening

— -- On a conference call with top Democrats ahead of the party’s summer meeting, Vice President Joe Biden said that he is still undecided about a run for the White House in 2016 and weighing whether he has the "emotional fuel" to endure a campaign, sources familiar with the session told ABC News.

“We're dealing at home with ... whether or not there is the emotional fuel at this time to run," Biden told DNC members, according to sources familiar with the call. "If I were to announce to run, I have to be able to commit to all of you that I would be able to give it my whole heart and my whole soul, and right now, both are pretty well banged up." The remarks were first reported by CNN.

Biden has been grief-stricken since the end of May over the death of his son, Beau, due to cancer, but has also been quietly stepping up calls to gauge support for a potential presidential candidacy. On Saturday, a sign of just how serious his exploration has become, Biden met privately with liberal icon Sen. Elizabeth Warren.

The moves -- and latest comments to DNC members -- have fueled speculation about whether he will run. Biden is expected to finalize his decision in the next six weeks.

“I just want the vice president to decide to do what’s right for him and his family,” Democratic presidential frontrunner Hillary Clinton told reporters in Iowa today. “He has to do what he has to do, but I’m just going to continue with my campaign.”

The Biden conference call today was hosted by the Democratic National Committee and billed as a chance for him to deliver the administration's case for the Iran nuclear deal.

ABC News dialed into the call -- which was not publicly advertised as open to the press but had no stated restrictions -- and was repeatedly disconnected by the operator after several minutes at a time.

As Biden discussed an academic analysis of how yellow cake is enriched, a brief history of U.N. resolutions against Iran and how he believes Iran will be blocked from the bomb, ABC News was abruptly given the boot.

“That resolution has three things in it,” Biden was explaining several minutes into the call. “You can’t get a nuclear weapon ...

Operator: “I am unable to let you listen to the call.” (click)

When ABC News re-dialed into the call, the operator again disconnected our reporter after a few minutes of listening.

“You need uranium to 90 percent to make a bomb,” Biden could be heard discussing. “That’s a longer process and 3.7 won’t get you there. Here’s the deal they have to ...“

Operator: “I’m sorry, due to customer request, I’m no longer allowed to allow you to listen to the conference call.” (Click)

A spokeswoman for the DNC did not immediately respond to ABC News’ request for comment. Some news outlets were allowed to remain on the call.

“He’s an interesting choice of a spokesperson,” given the 2016 chatter, one DNC participant told ABC News.

While the purpose of the session was to ostensibly lobby Democrats for the deal in his official capacity, to many political observers it was a chance for Biden to put his name –- and foreign policy chops –- front and center ahead of the party’s meeting. Biden won’t be speaking at the gathering in Minneapolis, but 2016 candidates Hillary Clinton and Bernie Sanders will.

“It’s ironic. He’s doing this call the day before the DNC meeting,” another DNC member told ABC News. “Good for him.”

The White House has so far not taken sides in the 2016 Democratic primary, but has publicly of late offered a boost to Biden.

Asked by ABC News whether it would be “easier” for the president if Biden did not run -– given divided loyalties to both his vice president and former secretary of state -– Obama spokesman Josh Earnest today demurred.

“I know there are some who have made that assessment,” he said. “Let me just say, that's certainly an assessment that other people are welcome to conclude. ... The vice president has more than earned the right to have the space and time to make a decision about whether or not he would like to be a candidate for president."

ABC News' Rick Klein contributed reporting.