With Thursday's announcement that Rep. Lincoln Diaz-Balart (R-FL) will not seek re-election in his Miami-area district, the number of Republicans not running for re-election to the House now amounts to more than 10 percent of the House Republican caucus, compared to less than five percent for Democrats.

Chris Cillizza at the Washington Post notes that the total number of House Republicans set to retire or seek other office is now 18, or slightly more than 10 percent of the 178 seats the GOP holds in the House.

By comparison, Roll Call's list of departing lawmakers shows that only 12 House Democrats are retiring, or slightly less than five percent of the Democrats' 255 seats.

The numbers are a little more even in the Senate, where five Republicans -- Kit Bond (R-MO), Sam Brownback (R-KS), Jim Bunning (R-KY), Judd Gregg (R-NH) and George Voinovich (R-OH) -- are retiring or seeking other office.

Four Democrats -- Roland Burris (D-IL), Chris Dodd (D-CT), Byron Dorgan (D-ND), and Ted Kaufman (D-DE) -- are also leaving the Senate.

Brian Beutler at TalkingPointsMemo reports that most of the 18 House seats vacated by Republicans this year are in solid GOP territory, but Diaz-Balart's heavily Latino district in the Miami area may be competitive in the fall.

While George W. Bush comfortably won the district in 2000 and 2004 -- by 58 and 57 percent, respectively -- the 2008 races saw the district lean more to the center: John McCain won with a 51-49 percent margin over Barack Obama.

The Miami Herald describes Diaz-Balart as "a passionate defender and architect of legislation to strengthen the US embargo against Cuba." The paper also notes reports that Diaz-Balart's brother, Mario Diaz-Balart, is considering running for the vacated seat.

Despite the higher retirement numbers for Republicans than for Democrats, much of the media's attention has focused on Democrats, with numerous commentators arguing that the numbers spell trouble for the Democratic Party in 2010.

In December, the Washington Post ran a story stating that strategists fear Democratic retirements "represent the leading edge of a wave of departures that could leave the Democrats vulnerable to significant losses in the 2010 midterm elections."

Reporting on four Democratic retirement announcements in 24 hours in January, Politico declared that "the grim outlook for Democrats in the 2010 midterm elections just got a little worse."

Aside from Diaz-Balart, this week marked the departure of two other lawmakers from the House. Democrat Diane Watson of California and Republican Vern Ehlers of Michigan both announced plans to retire.