Four House members now running for Marco Rubio's Senate seat

Just over a year into his House career, Rep. David Jolly, R-Fla., said Monday he plans to join the race for the Sunshine State Senate seat being vacated by GOP presidential candidate Marco Rubio.

He becomes the fourth member of the U.S. House to join the race.

Jolly narrowly won a hotly contested March 2014  special election in what was viewed as one of the few true swing seats in the country and a barometer of how the nationwide November elections might turn out.

But, as the Tampa Bay Timesexplains, redistricting in the state is likely to make Jolly's Tampa-area district much more Democratic.

Jolly cracked the door open for a Senate run after Chief Financial Officer Jeff Atwater announced he would take a pass, but the move became much more logical for him earlier this month after the Florida Supreme Court ruled that state lawmakers must re-draw the boundaries of eight congressional districts including his. Jolly represents Congressional District 13, one of just a few dozen truly competitive swing districts in the country, and most observers expect it to become a heavily Democratic district once the lines are redrawn to include voters in southern St. Petersburg.

Jolly is not the only GOP congressman vying for Rubio's seat. Second-term Rep. Ron DeSantis, from the state's northeast coast, announced in May that he would seek Rubio's seat as well.

Democrats are also facing a contested primary for the seat between two House members, as liberal firebrand Rep. Alan Grayson announced this month that he would challenge Rep. Patrick Murphy for the party's nomination, despite the fact that Murphy already has the backing of the Democratic Senatorial Campaign Committee.