I admit it. It took me a second to realize that the Jeb Bush who endorsed Marco Rubio today wasn't the former governor of Florida, who remains very popular with Republican primary voters and who has access to a cachet of top-dollar donors. It's his son, John Ellis "Jeb" Bush, Jr.
Jeb The Senior considered running for Senate and opted out; Gov. Charlie Crist remains the frontrunner; Rubio trails him and is running proudly to the right (and building his own political machine for the future at the same time). Jeb The Governor doesn't have much respect for Charlie Crist. I can write this without attribution from having spent enough time talking to Florida Republicans
who know both men. BTW: Crist still has no opinion on Sonia Sotomayor, and won't, until the Senate confirmation hearings. Jeb Jr. may or may not be a stand-in for his father, who will probably endorse Rubio closer to the primary, if he endorses at all.