Rep. Mario Diaz Balart (R) is running for the House seat that will be vacated by his brother, Rep. Lincoln Diaz-Balart — changing the complexion of the races in both South Florida districts.

Mario Diaz-Balart said moving over to the 21st district would be a “natural move” because he’s represented most of its communities during his years of public service. It’s also considered to be a little more friendly to Republicans than his current district.

Democrats said Cuban-American activist Joe Garcia, who came within 6 points of Mario Diaz-Balart in 2008, would be their first choice in the 25th district, but Garcia told Florida newspapers that he was committed to his post in the Energy Department.

Republican Alex Diaz de la Portilla, the Majority Leader of the state Senate, said he is considering a run. “I will make my final decision soon after thoughtful and deliberate consideration,” he said.

State Rep. David Rivera (R), who is currently running for the state Senate, said he may run as well.

Other Republican names that have been mentioned as possibilities in the 25th district are state Sen. Alex Villalobos, state Rep. Juan Zapata, Miami Lakes Mayor Mike Pizzi, Miami-Dade County Commissioner Bruno Barreiro and Carlos Curbelo, who is currently working as state director for appointed Sen. George LeMieux (R).

Lincoln Diaz-Balart said he wants to resume practicing law after he completes his term in the House.