Just how soft is Biden’s frontrunner status? Pretty soft even according to people who support him. Politico reported this weekend that a top state senator in New Hampshire who’s backing Grandpa Joe was so concerned about his low-energy campaign events in the state that he drove more than an hour to meet Biden in hopes of staging an intervention. Another piece up at the site today has Biden cheerleader Ed Rendell acknowledging fear among colleagues that his lead may be fragile, a house of cards that’ll eventually collapse under the weight of his gaffes and age-related concerns:

“There’s a clear worry among Biden supporters that he can’t be the front-runner from June of 2019 through July of 2020 … that eventually, the gaffes will pile up and he’ll come down,” said Ed Rendell, a former Pennsylvania governor and one of Biden’s most vocal supporters…

“It’s a deceptive lead, because it really doesn’t get tested until we get down to a narrower race in which, at some stage, people are going to have to say, ‘Is he our guy or not?’” said Paul Maslin, a top Democratic pollster who worked on the presidential campaigns of Jimmy Carter and Howard Dean…

Biden’s appeal to Democrats is so tightly tied to his perceived ability to defeat Trump that if he appears likely to suffer an early loss, one veteran Democratic strategist in Iowa said, “if you take any drop in [polling] support, you might bleed.”

Right, essentially Biden’s edge in the race is self-reinforcing. He’s the “electable guy”; the evidence of his electability is his lead in the polls (and head to head against Trump); but perceptions of electability are themselves contributing to his polling. If Warren or Sanders starts to outpoll him and air begins leaking out of the Biden “electability” balloon, how much might it deflate? An unnamed Dem who works for a rival campaign pointed Politico to Hillary’s sudden collapse in South Carolina in 2008 after Obama shocked the party by winning Iowa. She went from a huge lead to a blowout loss practically overnight, once it became clear to voters there that her nomination wasn’t inevitable. Once the balloon was punctured in the early states, it couldn’t hold air anymore.

Which brings us to the new early-state polls from CBS:

South Carolina is the one early state with a majority-black primary electorate and, not coincidentally, it’s the one state where Biden continues to run rings around the competition. He’s in trouble everywhere else, though — three points ahead in Iowa, behind in Nevada and New Hampshire. In every state except SC, Bernie is within three points of him or less. In fact, if not for Kamala Harris’s collapse, Biden might not have an edge on Bernie. He picked up 15 percent of Harris’s supporters since the last CBS poll (Elizabeth Warren picked up 29 percent!), helping to buoy him up against Sanders.

How long can that last, though? What if Harris has another good debate on Thursday night, or Biden a bad one? Certainly Warren’s going to come hard at him too. CBS went on to note that if you aggregate its polling from all four early states, including South Carolina, it’s not Joe who leads overall. It’s Warren, with 26 percent to Biden’s 25. She’s way ahead of him too when early-state voters are asked if they’d be enthusiastic if she/he became the party’s nominee, 46/29,

What kind of “frontrunner” is actually behind among the voters who matter most?

The standard dismissal of a survey like this one is that It’s Just One Poll and that other early-state results for Biden are better. Yes and no. It’s true that most polling in the early states shows Biden with a lead, but it’s also true that his leads there tend to be smaller than his national lead is. He leads by 11.7 points today at RCP in the national average but in Nevada his lead is closer to six points and in New Hampshire he’s actually down by less than a point in a three-way race with Warren and Sanders. The three polls of Iowa since July have each had him up, but two of those placed him in the three- to five-point range. If he were strong on the stump, you might treat all of those numbers as promising, with room for growth. For a candidate who’s weak on the stump, they seem tenuous.

Maybe the real takeaway from the CBS numbers is how resilient Bernie is in the early states. Biden, Warren, and Harris have gotten all the hype over the past few months, the first because of his frontrunner status, the second because of her steady polling rise, the third because of her collapse. But there’s Bernie, plugging away, poised for victory in every state except South Carolina. If he surprises the field by out-organizing everyone in Iowa and wins there, then leverages that momentum for victory in New Hampshire, he might cause a stampede of voters from Warren to him as the new progressive hope, giving him a commanding lead in the race. That’s the bind he and Warren are in right now — since it’s plausible that either one of them could win early and consolidate the other’s support, there’s no incentive for either to get out and endorse the other. They’re going to split progressives. The only question is whether Biden can capitalize.

Exit quotation from Warren, referring to persons who shall not be named: “We can’t choose a candidate we don’t believe in because we’re scared.”