Florida Gov. Charlie Crist (R) reportedly requested applications from three possible Senate appointees Friday, including Rep. Lincoln Diaz-Balart (R), as he considers whom to choose as a temporary placeholder when Sen. Mel Martinez (R) resigns.The Palm Beach Post first reported Crist’s request on Friday. In addition to Diaz-Balart, former U.S. attorney Bob Martinez (R) and former Florida Secretary of State Jim Smith (R) also received the six-page application form from Crist. Bob Martinez is not the same person as former Florida Gov. Bob Martinez (R), who had also been mentioned as a possible appointee.Crist said earlier in the week that he had developed a list of six or seven possible appointees to replace Sen. Martinez, who abruptly announced earlier this month that he will leave Congress as soon as Crist lines up a successor. Crist has indicated that he plans to make that pick before the Senate returns to business in September. Crist is only looking for a caretaker for the seat since he is running for Senate in 2010 and, at this point, is heavily favored to win.Diaz-Balart, who has endorsed Crist in the Senate race, was first elected to the House in 1992, and it’s unclear whether he has any interest in the appointment, which would in essence mean the end of his Congressional career in 2010. His brother, Rep. Mario Diaz-Balart (R), represents a nearby south Florida district. Some GOP insiders speculated that appointing Lincoln Diaz-Balart would create a House vacancy and special election that might be a tempting proposition for former state Speaker Marco Rubio (R), who is challenging Crist in the Senate primary. Rubio has repeatedly said he is in the Senate race to stay, but his former House district overlaps with Lincoln Diaz-Balart’s 21st district. Rubio spokesman Alex Burgos said late Friday that his boss’s efforts remain focused on only one race. “Marco Rubio is a candidate for the U.S. Senate. It’s not only Washington or bust for him, it’s also U.S. Senate or bust,— Burgos said in an e-mailed statement.House Democrats targeted Lincoln Diaz-Balart for defeat in 2008, but in the end, the race wasn’t even close. However, a special election could be a very different animal. The district has trended more toward Democrats in recent elections and Sen. John McCain (R-Ariz.) barely won the Miami-area district in the 2008 presidential race.