Tomorrow is the deadline to become a candidate in Hawai'i's Sept. 23 primary election, and some races are shaping up to be bruising battles while others will be cakewalks unless last-minute contenders emerge.

The U.S. Senate race between incumbent Daniel Akaka and fellow Democrat Ed Case has sparked the most interest, and both have begun buying advertising to increase their visibility. Akaka's campaign is far ahead in campaign cash, however, with more than $1 million on hand versus Case's $381,000.

Republican candidates for the seat include former Vietnam POW Jerry Coffee and attorney Mark Beatty. Winners from each party will face off in the Nov. 7 general election.

Incumbent Gov. Linda Lingle faces no serious competition in the Republican primary. Two lesser-known Democrats — former state Sen. Randy Iwase and Wai'anae harbormaster William Aila — are vying for the right to challenge Lingle in November. Big Island Mayor Harry Kim announced Friday that he would not run in the Democratic primary, ending months of speculation that had stalled some support for the others.

But a stampede of credible candidates are seeking the U.S. House seat for Central, Leeward, Windward and North Shore O'ahu and the Neighbor Islands, which Case is giving up to run for Senate. Democrats in the House race include former Lt. Gov. Mazie Hirono; state Sens. Colleen Hanabusa, Clayton Hee, Gary Hooser and Ron Menor; state Rep. Brian Schatz; former state Sen. Matt Matsunaga; and Honolulu Councilman Nestor Garcia. Republican contenders include former state Rep. Quentin Kawananakoa and state Sen. Bob Hogue.

Incumbent Democrat Neil Abercrombie faces no major competition from either party for the U.S. House seat that represents urban O'ahu.

Lt. Gov. James "Duke" Aiona has no Republican challenger in his re-election bid. Former Big Island state Sen. Malama Solomon is challenging Aiona from the Democrat side.

Six incumbent state senators and 18 representatives remain officially unopposed so far, though potential opponents have expressed interest in running.

Unopposed Democrat senators include Russell Kokubun, Brian Taniguchi, Donna Mercado Kim, Shan Tsutsui and Norman Sakamoto. Republican Sen. Fred Hemmings is also unopposed.

Unopposed House Democrats include Jerry Chang, Josh Green, Marilyn Lee, Hermina Morita, Bob Nakasone, Scott Nishimoto, Marcus Oshiro, Scott Saiki, Mark Takai, Dwight Takamine, Glenn Wakai, Tommy Waters and Ryan Yamane. Unopposed House Republicans are Lynn Finnegan, Barbara Marumoto, Colleen Meyer, Kimberly Pine and Cynthia Thielen.

Honolulu City Council Chairman Donovan Dela Cruz and councilmen Charles Djou and Rod Tam also remain unchallenged. Neighbor Island council members with no opposition include Fred Holschuh, Donald Ikeda, Bob Jacobson and Angel Pilago on the Big Island; and Michelle Anderson, G. Riki Hokama and Danny Mateo in Maui County.

Also in Maui County, school board member Mary Cochran and Office of Hawaiian Affairs trustee Boyd Mossman remain unopposed.