"He's a little bit behind," said Tom Henderson, the Democratic chairman in Polk County, the home of Des Moines.
"Most campaigns use summer to set up field staff and are ready to roll to organization in the fall," he said. "If he waits too much longer, it's probably going to be too late."
But Henderson said it's still possible for Biden to enter the race in August and build an organization that's capable of competing in the early February Iowa caucuses by November or December.
This week, as media speculation over a Biden candidacy has re-ignited, the vice president is in Delaware with his family, celebrating his granddaughter's birthday.
Though he hasn't put together any sort of presidential campaign committee, a group called Draft Biden recently added a former Beau Biden adviser, Josh Alcorn.
Biden supporter (and Clinton opponent) Dick Harpootlian, a former South Carolina Democratic chairman, said he was encouraged after speaking with Alcorn.
"This is an indication that there is at least some desire from the people that surround the (vice president) that this process of getting him into the race has escalated," Harpootlian said Monday.
He said speculation about a Biden candidacy is now rampant.
"Since this news came out over the weekend, I've had calls this morning from five major political people in South Carolina, two from Hillary people who would jump to Biden," Harpoolitan said.
While Democrats' loyalties might be split, the relationship Biden and Clinton has never been on bad footing. The closest the two had to a public spat was two years ago when Clinton told a crowd that the two had been at odds over the raid that killed Osama bin Laden -- with Clinton supporting it and Biden in opposition.
Hovering above it all, too, is the death of Biden's son, Beau. His family is still mourning, and it complicates both the timing of a Biden run and how his opponents would have to handle him.
The case for Biden is this: If Hillary Clinton is hampered by questions of trustworthiness, the vice president's liability is just the opposite -- he can't help but say what's on his mind.
It's resulted in embarrassing moments like his 2010 hot-microphone comment in President Barack Obama's ear that the health care law is a "big f---ing deal."
But that quality has also allowed for some of politics' most touching moments -- like his 2012 speech to the families of fallen soldiers in which he discussed the death of his own wife and daughter.
And in a political environment in which a tell-it-like-it-is character like Donald Trump
has risen to the top of the Republican field, that might not be a bad thing.
Biden's tendency to gaffe, "once a negative, could be a positive," Patti Solis Doyle, a Clinton 2008 campaign manager who then worked for Biden once he became the vice presidential nominee, said Monday on CNN's "The Lead" with Jake Tapper.
But there's another side to the authenticity coin that has also at times undercut his image. He's been mocked for his tendency towards a touchy-feely approach
on Senate swearing-in days, and he's also offended people with his glibness. Conservatives widely view him as a punchline.
Nonetheless, through six-and-a-half years in the White House, Biden has maintained contacts in early voting states like Iowa and New Hampshire, where some local Democrats say they're eagerly awaiting his decision.
Iowa state Rep. Bruce Hunter of Des Moines, who endorsed Biden during his 2008 campaign and has met in person with the vice president several times since, said that "there's been a lot of unofficial groundwork -- people like myself waiting for a decision before we do anything."
He said Clinton's struggles to demonstrate her trustworthiness -- while not fatal for the former secretary of state's candidate -- have created an opening for Biden.
"They're definitely warning signs and probably do leave room for a candidate to come in and challenge her," Hunter said. "And I think Joe's always been the genuine article: Whether you like it or not, you know where he stands."
The 72-year-old Biden's friends and advisers are urging him to keep the door to a presidential campaign open. On top of the urges to run from his son Beau Biden before his death in May, some of Biden's allies hope he'll decide in the coming weeks that a late entry into the race is viable.
A skilled retail politician with deep relationships in the White House and on Capitol Hill, Biden isn't the clear threat to Clinton that one potential opponent who passed on the race -- Sen. Elizabeth Warren -- would represent, but Democrats everywhere say he could test Clinton.
What's less clear is whether Biden has time to build the sort of campaign infrastructure it would take to become more than a nuisance, or even overtake Sanders as Clinton's toughest opponent.
The Clinton campaign has said for months that she's steeling herself for a stiff battle for the Democratic presidential nomination.
Now, she's facing the possibility that it might come on two fronts: The ideological confrontation she's already facing with Sanders and O'Malley, and perhaps an even tougher test of whether she can survive questions about her honesty and trustworthiness as stories continue to trickle out about her use of a personal email address on a private server while secretary of state.
But Clinton's aides pointed to her fundraising strength -- she raised $45 million in the three months after announcing her candidacy.
Her campaign is spending $2 million of that money to launch biographical television advertisements starting Tuesday in Iowa and New Hampshire. Those spots highlight less-known elements of Clinton's biography, such as the story of her mother Dorothy's challenging childhood, in an effort to demonstrate that the former secretary of state has been fighting for causes dear to liberals her entire life.
She also has a head start in organizing. Clinton's campaign has staffs in place in Iowa, New Hampshire, South Carolina and Nevada, and hired 51 temporary field operatives to recruit volunteer bases and court influential Democrats in the other 46 states.
"In the coverage, it gets lost: She has the most money, and she's beating every Republican in most of the polls. So you can't really ask for much more than that," Clinton communications director Jennifer Palmieri said on CNN on Sunday.
Other Democrats who, like Palmieri, have worked in President Barack Obama's administration, expressed affection for Biden echoed the idea that it could be too late for him to seriously challenge Clinton.
Dan Pfeiffer, a former senior adviser to Obama who worked closely with Biden since the 2008 campaign and is a Delaware native, said he is skeptical of how seriously Biden is considering a run.
"Whether he gets in or not, I don't really know. Certainly if he does, he'll a legitimate candidate who has a great record and would be a great challenge for Hillary Clinton," Pfeiffer told CNN on Monday. "But Hillary Clinton is well ahead of him, not just in the polls, but in the organizational work you have to do to win the nomination. She's been organizing Iowa and New Hampshire for months, while he hasn't been working the scene at all."
"This would be very challenging," Pfeiffer said. "But he certainly has more than earned the right to run if he chooses, but it would be a hard piece of business."