Former Rep. Charles Djou (R-Hawaii) will run for his old seat, according to his state's GOP party chairwoman.

Hawaii Republican Party chairwoman Pat Saiki said on Hawaii News Now that Djou will enter the open-seat race this week, giving Republicans an outside shot at winning a heavily Democratic district.

Djou won a three-way special election for the seat in 2010 and served in Congress a few months before losing that fall to Rep. Colleen Hanabusa (D-Hawaii). She defeated him by a 10-percentage point margin in a 2012 one-on-one rematch.

Hanabusa is vacating the seat for a primary run against Sen. Brian Schatz (D-Hawaii), who was appointed to the seat in late 2012.

President Obama won almost 70 percent of the district's vote in 2012, though Djou won 47 percent there in his 2010 general election bid and 45 percent in 2012.