Why was the Democratic establishment so united behind Clinton in the beginning?

[Mr. Morden]

I think the dominant narrative here of how party elites wield power is wrong.  No individual actor has the power to shift the odds of any one candidate winning the nomination up or down by all *that* much.  So you're talking about the collective actions of a large-ish group of people (big money donors and party leaders).  Each of these people realizes that their leverage is very constrained, so their incentives drive them to back the person who they think is going to win the nomination anyway, which has the potential to drive a massive bandwagon effect.

These folks thought Clinton was inevitably going to win the nomination anyway (she was leading the polls by like 50 points) and they wanted to be on the winning team.  It didn't hurt that they also thought she would be a pretty good GE candidate (remember that her favorability #s were still reasonably good in 2014), and that many of them believed that a coronation would probably be better than a combative primary.  But they were going with the person who they thought was going to win even without their support.  And they did this because they wanted as much influence as possible with the person who they thought was most likely going to be elected president, and because they didn’t want to give said person a reason to seek vengeance against them.  They would have similarly rallied around Joe Biden or Kirsten Gillibrand, or any other “establishment” figure who had a massive lead in the primary polling and appeared to be popular enough among the general electorate to win the presidency.

[Mr. Morden]

I think the dominant narrative here of how party elites wield power is wrong.  No individual actor has the power to shift the odds of any one candidate winning the nomination up or down by all *that* much.  So you're talking about the collective actions of a large-ish group of people (big money donors and party leaders).  Each of these people realizes that their leverage is very constrained, so their incentives drive them to back the person who they think is going to win the nomination anyway, which has the potential to drive a massive bandwagon effect.

These folks thought Clinton was inevitably going to win the nomination anyway (she was leading the polls by like 50 points) and they wanted to be on the winning team.  It didn't hurt that they also thought she would be a pretty good GE candidate (remember that her favorability #s were still reasonably good in 2014), and that many of them believed that a coronation would probably be better than a combative primary.  But they were going with the person who they thought was going to win even without their support.  And they did this because they wanted as much influence as possible with the person who they thought was most likely going to be elected president, and because they didn’t want to give said person a reason to seek vengeance against them.  They would have similarly rallied around Joe Biden or Kirsten Gillibrand, or any other “establishment” figure who had a massive lead in the primary polling and appeared to be popular enough among the general electorate to win the presidency.

Obama gave Hillary control over the DNC infrastructure, she had DWS & co. openly sponsoring her.

http://www.politico.com/story/2015/06/impartial-dnc-finance-chief-helps-hillary-clinton-118558

I'm talking about the invisible primary though, which is the maneuvering that happened in 2013/2014, before the Clinton campaign even existed as a formal entity.

[Mr. Morden]

Again, I'd maintain that the questions surrounding Biden's deliberations in 2015 misses the point, which is that Clinton had already won the "establishment lane" in the invisible primary before 2015 even began, before the midterms, and many months/years before she formally launched her campaign.  She won it in 2013/14, and she won it not because party elites all got in a room together and conspired to insure that she be the pick, but because each of those party elites individually concluded that she was going to win anyway, and so they wanted to be on her side.  But then the collective aggregate of those individual decisions enhanced her chances of winning a great deal.

Other frontrunners of years past have also done some field clearing by winning the invisible primary, but none who were not either incumbent presidents or vice presidents have done so quite as thoroughly as Clinton did.  Part of it is that her lead in early polling was so enormous so consistently and at such an early stage, part of it is that there was always a suspicion that Biden (either by virtue of his age or by virtue of being gaffe prone) wasn't going to make the transition to the top job, and so Clinton was the de facto heir apparent instead of the VP, and part of it is that she was thought of as more of a known quantity than many frontrunners of years past.  GW Bush also had an enormous polling lead in 1998/1999, but he was new to the national stage, whereas Dem. elites in 2014 thought they already knew enough about Clinton's strengths and weaknesses (oops).

And yes, part of it is that she's a woman, and the thinking was that it was time for a woman.  Or at least, party elites thought that Democratic primary voters would think that.  They thought that Obama's status as first black president had energized a segment of Dem. primary voters in 2008, and that that would be replicated for women in 2016.  I can't find the story right now, but I do recall seeing reporting on Cuomo's deliberations years ago, with his thinking being that he'd be blamed as a party pooper for spoiling the nomination of the first female Democratic nominee and president if he ran against Clinton, as if he was trying to rob America of another first.  IIRC, there was some talk of that being part of Biden's thinking as well, and I'm sure they weren't alone.