State Sen. Gary Hooser, who represents Kaua'i and Ni'ihau, said he plans to run for lieutenant governor in 2010.

In a letter to supporters, Hooser says he wants to play a stronger role in leading Hawai'i toward a positive and sustainable future.

The senator was a vocal advocate of requiring an environmental impact statement before Hawaii Superferry could begin offering high-speed interisland service.

Hooser authored a law enacted last year making Hawai'i the first state to require solar water heaters in new homes.

In 2006, the senator finished fifth in a 10-way primary race for the Democratic nomination to represent Hawai'i's 2nd congressional district.