But Biden has not only been under attack from Trump.
The left/progressive wing of the Dems have also been going at him since he declared. And other shaky moments have shown the Trump strategy may have only escalated the situation against Biden and might actually give Warren a quicker path, thus actually making the process or running against Trump somewhat easier for her if her momentum holds up.
I'm still for Bernie but am annoyed as some of the stridency of Bernie or Bust -- Bust means Trump. Warren has been under attack from the Bernie left/Jacobin crowd who are throwing the kitchen sink against her: she's a deceiver, she takes big money and tells others not to, her education plan is bad, she stole Bernie's ideas, she is a Hillary plant - etc.
There are serious issues with Warren on education and Bernie's plan is much better and Bernie we know is adamantly pro-union since forever and when he shows up on a picket line we know he means it. But there has also been an article circulating about Bernie's top assistant Nina Turner who supposedly was involved in a big way in ed deform in Cleveland, with views that compare with Warren's old ed views, posted on the Intercept.
Nina Turner, Bernie Sanders’s Campaign Chair, Led Charge for Education Reform as Ohio Legislator
Here is a pro-Warren piece in Esquire: What We Learn from Elizabeth Warren.
Trump and crew may be laughing at the idea of how he can mock and rattle her plus the idea that there are a lot of men and many women who will not vote for a woman plus the center Dems who are very nervous over Warren.
It is a mistake for Dems to think that any one of them can beat Trump and that he is weakened so much now. But Warren at this point is looking like she can take him on. Hillary still got 66 million votes and Warren doesn't carry her baggage.
However, if Warren look real strong, the Trump/Republicans will swiftboat her with anything they can dig up. And if they can't dig something up they will make stuff up and be believed by their core.
Then there are the rumors of Hillary sitting in the wings to rep the center Dems if things go sour -- she thinks all she has to do is flip not that many votes from last time and many people who sat it out will come back after the Trump years. I even commented on a socialist FB page how I still prefer her to Trump.
There is another angle. Trump gets convicted in the Senate due to some Republicans seeing a better path for them with Pence as president running in 2020. An interesting article in Politico explores this idea.