Marco Rubio doesn't have Jeb Bush's support, but he's got the next best thing.

The former governor's son, George P. Bush, announced Thursday that he will back Rubio over Florida Gov. Charlie Crist (R) in Florida's Senate primary. It's the latest development in a will-he-or-won't-he drama over Jeb Bush's endorsement.

While George P. Bush's backing is nice, it could signal that his father isn't getting involved. The senior Bush would make a bigger splash with a Rubio endorsement, but he could also irritate certain elements of the national GOP.

It might also be the former governor putting out a feeler to see what the reaction is.

The NRSC is still behind Crist, though Rubio continues to build steam in the primary. George P. Bush has also endorsed developer Armando Gutierrez in the race to face Rep. Alan Grayson (D-Fla.), while the national GOP has sought another candidate.

“I’ve known Marco Rubio for years and saw what he could do during the six years he spent working alongside my father promoting ideas and reform-based conservatism," George P. Bush said. "He is a rock-solid conservative and the leader Floridians deserve in the U.S. Senate to advocate for limited government and greater personal freedoms."