Money. Both in terms of fundraising and lost opportunity costs. Right now, HRC is raising close to $40million/month, $10million of it from small donors. She is being very thrifty with it; amassing a war chest for the General, setting up organizations in key states.
Bernie is raising $40+ month [or was, we don’t know if this will continue at that pace], but he is burning thru it twice as fast as HRC. To net 6 delegates last night, he spent $2.5million to her $500k. To lose 5 states last week he spent 3times what she spent. If you can do math, you see where this is going. HRC will continue to spend as little as possible to win NY, PA, MD, CT, whereas Bernie will have to outspend her 3-4/1 to break even in those states—and still probably lose them all. Which does nothing to help him close the gap in the delegate race.
THEN, there’s CA! Lots of delegates, very expensive to advertise there! HRC would rather not spend big there, since it will not be contested in November, but Bernie may force her to spend $10million. He will spend $20-30 million there, if he stays in. YET, CA is so proportionally divided, that they both walk away with over 200 delegates there unless Bernie gets over 70% of the vote!
Math. Money. That is what is really motivating the ‘establishment’ types like Sherrod Brown, Ed Murray, Tammy Baldwin, etc. Not to mention the fact that HRC’s Superpacs can buy ad time in Sept/Nov for ½ the price if they lock it in now, rather than in July. PLUS, no way Trump self-funds a General election. He would—with little time to do it—have to get GOP donors to move their funds to his race, which will cost down-ticket goopers dearly. Lost-opportunity costs for the Dems if they have to spend big $ in CA.