ll 51 state House seats will be up for grabs this year, but only 19 races include primary challenges. That’s a shame. State representatives wield huge influence over life in Hawaii, and the electorate would benefit from more vigorous competition.

Still, 10 of the 34 Oahu races do have more than one candidate seeking the nod from his or her party. The Honolulu Star-Advertiser focuses its House primary endorsements on those contested races: up through District 40 today, with the remainder of House contests on Friday.

» In the 23rd District (Manoa, Punahou, Moiliili), we endorse incumbent Isaac W. Choy over challenger Nathaniel Keoki Kinney in the Democratic primary. Choy, 60, who describes himself as the only certified public accountant in the state Legislature, has represented the district since 2008. Choy has a long history of involvement in the community and a detailed grasp of issues affecting the University of Hawaii, which employs or educates many of his constituents. Choy’s lack of support for same-sex marriage and his early support for a limited pension tax inspired Kinney to enter the race, but the energetic challenger lacks fiscal expertise that Choy brings to this seat. The winner here will run unopposed in the general election since there no other candidates from other parties.

» In the 33rd District (Halawa, Aiea, Newtown), which is being vacated by Mark Takai for a U.S. House run, our choice in the Democratic primary is Tracy Arakaki. A member of the Aiea Neighborhood Board for 15 years, Arakaki, 49, is familiar with district concerns, including traffic caused by rail system construction, crime and what he sees as foot-dragging by Hawaiian Electric in processing applications by area residents to install solar systems. Arakaki’s business experience includes running his own screen-printing firm for 15 years and a television production company for the past 10. He says that as a former news cameraman, he knows the importance of transparency and honesty, which are values that would serve him well in the Legislature, should he prevail over Republican opponent Robert C. Helsham Sr. in the general election. Arakaki’s opponents in the primary are Sam Kong and Arnold Wong.

» In the 36th District (Mililani, Mililani-Mauka, Waipio Acres), our choice between the two Democrats is veteran community activist Marilyn B. Lee, 74, who was the district’s representative prior to being ousted in 2012 by Republican Beth Fukumoto Chang — whom Lee will again face in the general if she prevails in the primary over Luella Costales. Costales’ credentials are impressive, but Lee has superior experience. She served in the Legislature for 16 years, was elected last year to the Mililani Neighborhood Board and also is a member of the Hawaii State Commission on the Status of Women. Prior to retiring, she was a registered nurse at Wahiawa General Hospital for 25 years; during the Vietnam War, she was in the Navy Nurses Corps.

» In the 38th District (Waipahu), our pick in the Democratic primary is incumbent Henry Aquino. He faces former state Rep. Alex Sonson, who served in the House from 2002 to 2008 before losing Senate primaries in 2008 and 2012. Aquino, 37, ran unopposed in the 2012 general election, just as he will this year if he prevails over Sonson. Aquino, who is executive director of the Waipahu Community Association, serves as chairman of the House Public Safety Committee, and we see no reason why he should be denied the chance to continue in that position.

» In a rarity for the Legislature, the incumbent in the 40th District (Ewa Beach, Iroquois Point) is a Republican, Bob McDermott, 50, who has no primary election foe and so will advance to the general. He will face the Democratic victor: either entrepreneur Rose Martinez, 54, or caregiver Isaiah N. Chong. Both are political neophytes, although Martinez has run unsuccessfully twice before, for this seat in 2012 and a City Council special race in 2010.

Based on her breadth of professional experience and community service, Martinez gets our endorsement today. She has been an aide and policy analyst in the Legislature; she also holds a master’s degree in public health and has worked in that field, which could be insightful on statewide health issues such as the ailing public hospital system.

Honolulu Star-Advertiser Endorsements: July 20 through July 27, we present our picks for the primary election’s major contested races.