Picking a siting Senator is not a very good idea, regardless of Brown's undeniable merits, because in a year of wild anti-establishment wave that wouldn't play well, especially with Hillary. Also, that would amount to losing a Senate seat, which isn't a good idea either.
To some degree, it also goes against Castro, a freaking sitting member of Obama's cabinet. Aside of "he's a Latino", there's literally nothing justifying such a pick: you can't put Texas in play and he's just an empty suit.
Shes not hoping to put TX in play, but most Millineal Latinos dont speak fluent Spanish; otherwise, Rubio would of been nominee. He is young and the SW is in play anyways. If its a close election, she will need every Latino vote possible
