Vice President Joe Biden met with political advisers Monday at his residence in Washington, D.C., continuing talks about a possible run for the Oval Office in 2016, CBS News confirms.

The Biden team's conversation, according to a Wall Street Journal report, included a discussion on when an announcement would be made and whether an earlier campaign launch could assure the vice president a spot in the first Democratic debate.

The first debate for the Democratic candidates is scheduled for October 13.

After the vice president's appearance last week on "The Late Show with Stephen Colbert," when Biden seemed to be openly wrestling with whether he had the emotional energy to run, many considered it a likely sign that he would not enter the race. Monday's meeting with advisers keeps open the conversation surrounding a possible Biden campaign.

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Over the last few days, some Democratic donors are also escalating calls for the vice president to mount a challenge against Hillary Clinton.

In a letter circulated Friday signed by nearly 50 prominent party fundraisers, potential donors pledged their support for Biden, calling him "an authentic leader" who has had "spectacular success" with President Obama.

"To finish the job, America needs a leader who is respected both home and abroad, and who understands the real challenges facing American families," the letter states. "In our opinion, the next president must be Joe Biden. If he announces he's running, we're all in. It's a campaign we know he will win."

Meanwhile, at a New Hampshire Democratic Party convention Saturday, Draft Biden supporters are continuing their ground campaign. The group, which has been working for months to recruit Biden for a 2016 bid, cited the Democratic donor memo as proof of increased interest. In a internal memo obtained by CBS News, Draft Biden staffers boasted that since the vice president's "Late Show" interview, they've seen an 800 percent increase in daily sign-ups for the organization.

The group working to build an infrastructure for a Biden run has not been told to stop its efforts, and that's provided hope for supporters that Biden will eventually jump into the race.

Biden himself has provided no hints about which way he's leaning.

And with rumors continuing to swirl around a Biden bid, Clinton has ramped up her own efforts to lock in her donor base. In recent days, the Clinton campaign reached out to at least one Democratic donor who is waiting to see what Biden decides to do before taking a more active role raising money for her campaign.

Should Biden run, the timing for a campaign announcement is still uncertain. While some see the mid-October debate as an important deadline to meet, others have raised the possibility that an official launch could come as late as November -- or even later.

CBS News' Julianna Goldman, Steve Chaggaris, and Jacqueline Alemany contributed to this report.

Below is a copy of the Democratic donor letter obtained by CBS News: