Just to note that when it comes to counting Democratic delegates the media narrative is that the Clinton campaign “can’t catch up.” But it is also worth noting that the Obama campaign can’t win either. He would have to take over 70% of the remaining to-be-pledged delegates, which is unlikely.
While proportionate representation favored the Obama team early in the race, it is now the bulwark of the Clinton campaign. The race will still come down to the Super Delegates and/or the convention. So there is no particular reason for Hillary to drop out of the race, and very good reasons to stay in it. If she dropped out after TX and OH, and Obama went on to win in the Fall, she might be looking at 2016 before being able to run again, and that is unrealistic.
Also, a lot can happen between the Puerto Rico primary June 7 and the August 25 convention opening, during what is certain to be some intense horse-trading. The Obama campaign seems to be banking on talking Senator Clinton into conceding before the convention, but the bottom line is that if she gives up she will be giving up her lifelong dream of being President, whereas he is young enough to give it another shot later — particularly if he is in the #2 spot on the ticket.
I doubt that Senator Clinton would give up the fight when there is any chance at all of winning it. I think the fact that Harold Ickes has been given an entire floor of the Clinton national HQ for his delegate search operation is signal enough that they are in it for the long haul. But they need to begin now lowering expectations for TX and OH just in case things don’t go as planned. By tagging them “firewalls” and “must wins” they have placed themselves at unnecessary risk. The only “must win” right now is the floor fight.