Of course they will attack whoever the Democrat is. They attack every Democrat. And they lose elections quite often because a lot of the attacks are stupid and don’t take. Biden is old is taking because there is a lot of evidence for it. IF they attack Kamala for whatever is it going to be as persuasive. I don’t think so.
What polls are you looking at?
Good question. Let’s say in November, because that’s the reality and not a hypothetical.
(And I notice folks posting here without numbers; my intent was to encourage numbers for context, so get on that, y’all. 
)
Polls show Biden within the significant error of most polls as tied with trump. I.e within a point or two.
Biden has got to be close to 50% to win right now. Most of the polling I’ve seen massively, massively overstates what I believe the final 3rd party vote share will be. I’d rate almost all other Democrats lower - in the 30% or less range. If they want to swap Biden out it needs to be for a celebrity. Turns out for example, Taylor Swift is eligible for the presidency (will be 35 just a month before required). Taylor swift herself I’d rate at 75% favorite, and several other celebrities like Oprah Winfrey I would rate as better than Biden.
Just because you are within the significant error does not mean things are 50/50. Significant error is generally used to prove that one think is highly likely (over 95% or more depending on the topic) than another. A person with 25% chance of winning is going to be within significant error in polling.
That is not how math or polling works. But a difference of 1 or 2% is within deviation.
Right now I’d put Biden at 60-40. Yes, I know he laid an egg at the debate, but he’s running against the only person on the planet whom he could beat after such a fiasco. And just ask President Romney about how incumbent presidents do after flubbing their first debate. We still have abortion as the ace in the hole and with the way that the backward states are tripping over themselves trying to criminalize health care, that issue stays red hot in November.
Should he step aside, I’d give Harris even odds to win, perhaps a bit less for Whitmer (whose time could well come in 2028).
Is this a joke or are you serious?
I think Trump has shown us that name recognition alone (i.e. celebrity) gets votes. If the goal is to win, Swift is as good a choice as Biden, perhaps better.
She would have a rather steep learning curve, but she seems like a smart person, and a good one… I’d certainly consider voting for her. I doubt if she’s remotely interested, though, and she seems content with her current career trajectory.
Pre-debate I would put Biden at say 52% post debate 40%. Basically, he lost a bit but is still close. I put Harris’ chances at probably 25%.
In terms of the chances that changing the candidate would make the difference:
I think that there is about a 8% chance that switching to Harris would win an election that Biden would lose, about a 23% chance that switching to Harris would cause her to lose an election that Biden would win. About a 17% chance that the Dems would win no matter which one they put, and a 52% chance that Trump would win no matter which the Dems put.
As for the other candidates I would say that there is maybe a 10% chance that they would win, and if they would win than any Dem would win.
Serious. Name recognition both gets votes, and because they are already “known” any narrative republicans try and paste on them would be harder. That only applies to the very biggest of celebrities, not like Kathy Griffin or something. Edit to add, this is contigent on Biden dropping out and supporting them too, not some sort of end run around him.
Accepting what I actually feel is a very dubious premise, do you feel that Taylor Swift is better known than Joe Biden?
I’ll use my mother as an example. She knows who Joe Biden is. I doubt very much she knows who Taylor Swift is.
I don’t think this is a good analogy or comparison. Romney was going up against one of the best campaigners in history, and a guy who was 30 years younger than Biden at that time. The consensus of everyone was that Obama just had a bad night, and Obama was able to shed off that bad performance just days later in the second debate. There’s no guarantee Biden is going to pull an Obama.
Contrarian opinion: I have no idea. It’s impossible to say. There are too many variables to consider, and 4 months is still a long time.
If you got Romney or someone truly charismatic, with a positive message, relatively acceptable to the majority, and who is immune to trolling, then they’d have a 100% chance of winning against Trump.
As you go further away from that, the possibility changes.
In general, you can depart from it in the two directions: Charisma or acceptability.
Biden has acceptability and we can see that if you have that and fairly little charisma, you still have a roughly 50% chance of winning.
I don’t believe that, with today’s emphasis on demonization, that you can go very far from the middle and win on charisma. If you are just a little too friendly towards solar power then you’re an anti-modernity, communist hippie; if you’re just a little too in to prosecuting illegal immigration, then you may as well get in line for your KKK card. There’s going to be a massive engine that’s laid in decades of prep work to bag you, tag you with the appropriate slurs, and throw you away in the big piles of “Generic D” and “Generic R”. You’re not a person, not a human being, not a unique and distinguished individual, you’re just another of the costumes that the Deep State Man puts on to play the part of a representative of your enemy’s political party.
In general, you have the range from Obama to Nikki Haley to play in. You can win in that range with charisma. Outside of it and you’re going to be playing with fire.
The drama around Biden dropping out and selecting some random person would, immediately, turn them into a celebrity.
Most celebrities become so in a second. There’s very few who slowly grow and continue in fame for decades.
Anita Hill popped out of nowhere and, within weeks, everyone had an opinion of her. Same with Monica Lewinsky, Stormy Daniels, etc. All you need is a good story that everyone’s talking about, and the demand for information will be so great that everyone will be slammed with more information than they ever wanted to know within days, the gossip train will take off, and suddenly we’ll all be experts.
This post links to several prediction market sources:
Manifold currently gives (for “if X is the nominee, will they win the presidency”):
Joe Biden: 31%
Kamala Harris: 38%
Gavin Newsom: 49%
Note though that these numbers are a few ticks higher than they would be in isolation. The reason is that assuming they became the nominee bakes in an assumption about some event in their favor: Biden having a better debate, people publicly putting support behind Newsom, that kind of thing. Or, thinking about it in reverse: Biden’s 31% is high because it excludes the case where he has a second debate as disastrous as the first, because no way he would be the nominee then.
The polls are for the popular vote. But what matters is the electoral vote. And currently it seems that a Democrat needs to have a 3% positive popular vote margin to win the electoral vote.