Florida Rep. Lincoln Diaz-Balart, a Republican lawmaker for nine terms, will retire at the end of this term.

Diaz-Balart is the brother of Rep. Mario Diaz-Balart, R-Fla., who represents a neighboring congressional district. 

Lincoln indicated last summer he was “seriously considering” an offer from Florida Gov. Charlie Crist, also a Republican, to be temporarily appointed to the Senate when former Sen. Mel Martinez, R-Fla., resigned. Instead, Crist appointed Sen. Sen. George LeMieux, R-Fla., to fill out the balance of Martinez’s term.

Democrats have long viewed both seats held by the Diaz-Balart brothers as potential pickups. Lincoln faced his toughest re-election in 2008. But he ultimately defeated former Hialeah Florida Mayor Raul Martinez with 58 percent of the vote. The vote was nearly split between President Obama and Sen. John McCain, R-Ariz., in the 2008 presidential contest.

There is speculation that Mario could seek election in his brother’s seat, which is considered to be a safer Republican district.

Lincoln Diaz-Balart was born in Havana, Cuba and was one of the first-Cuban Americans to win a seat in Congress. He’s a former Democrat who later joined the Republican party in the mid-1980s. He previously served in the Florida House and Senate.

Diaz-Balart has long been involved in Cuban-American affairs. He advocated the assassination of former Cuban leader Fidel Castro. He also tried to help the Florida relatives of Elian Gonzalez secure his custody from his Cuban father.

Diaz-Balart becomes the 18th House Republican and the second in as many days to announce they won’t stand for re-election later this year. Only 12 House Democrats have declared their retirements.

Fox News' Nancy Harmeyer and Dianne Fernandez of WSVN-TV in Miami contributed to this report.