Castro isn’t ready for prime time. (Neither was Obama — what would Lyndon Johnson have done with Mitch McConnell? Maybe that’s one reason the Dems are leery of someone with no gray hair.) The attack on Biden at the September debate was a real killer. It just reeked of rehearsed insincerity — like Rubio’s “He knows exactly what he’s doing” mantra in the 2016 GOP race— clear evidence that Castro cared more about himself winning the nomination than his party winning the White House. Having that set of priorities isn’t necessarily a sin, but not having the skill to pretend otherwise is fatal to a campaign.