My take on the state of play for the Dem. nomination (get used to a lot of these!) in order of the latest polling.
Biden: "officially launched his campaign" this weekend, which is effectively meaningless in this day and age. Has what seems like a prohibitive edge in the polls (far above what Donald Trump polled in a similarly clown car primary scrum) but a lot of people seem to forget that Joe Biden is… not that good at this. His style is retail politics and pressing the flesh and I suspect the first gaffe he makes will utterly destroy his candidacy because he won't be able to recover. And it being Biden, he'll make more than one.
Sanders: someone pulled up footage of his honeymoon in the Soviet Union in the 80s, and the New York Times ambushed him in a phone interview with pro-Sandinista comments he made around the same time. For the DSA crowd who already wear "Venceremos!" buttons this isn't exactly a disqualification (of course few people know what an ogre Ortega eventually turned into, but remarkably that didn't come up much) Still believe he's the actual front runner once the wind goes out of Biden's sails, but this shows that attacking Sanders from the right will happen quite a bit (and if you think it's bad now, imagine the GOP during a general election campaign)
Warren: whomever in her campaign came up with posting detailed policy proposals to Medium first thing in the morning is a genius, and getting out ahead on the attempts to overturn Roe v. Wade is politically sound. Still very much a serious contender, now more than last month. (But bear in mind even at 3rd, she's still at single digits in polling. That's what happens with 22 candidates.)
Harris: Biden stole her "candidate of the moderate establishment" mantle and she's done little since to make up for lost time. Not looking good.
Buttigieg: had a great day on Fox News where he literally got a standing ovation. The media love him, he pretty clearly is Obama 2.0 in terms of demeanor (and policy, for that matter). However, Obama was, shall we say, a touch better at attracting the black vote. With Mayor Pete literally polling at 0% among African-Americans in the South Carolina primary this is campaign-ending if not fixed and fast.
Beto: Just stop.
Everyone else: Not a factor.
deBlasio: Beto makes him look serious.