Veteran state Rep. Mark Takai coasted to an easier-than-expected win over state Senate President Donna Mercado Kim in the Democratic primary for Hawaii’s 1st Congressional District seat.

The win sets up a Nov. 4 showdown between former U.S. Rep. Charles Djou, who faced only nominal opposition in the Republican primary. Both candidates have military backgrounds and served in the Middle East: Takai is a lieutenant colonel in the Hawaii National Guard and Djou is a major in the Army Reserve.

Others in the Democratic primary — Honolulu City Councilmen Stanley Chang, Ikaika Anderson and Joey Manahan; state Sen. Will Espero; and human rights activist Kathryn Xian — trailed far behind Takai and Kim.

Voter polls had Kim as the early front-runner, but Takai saw a surge in the closing weeks of the campaign. A February Hawaii Poll, sponsored by the Honolulu Star-Advertiser and Hawaii News Now, showed Kim with a 10-point lead, but a follow-up poll late last month showed the two candidates in a dead heat.

According to the latest tally available at press time, he captured 43 percent of the primary vote to Kim’s 27 percent.

Takai, 47, said he was surprised by the wide margin of victory, and credited his volunteers.

He first won election to the state House in 1994 representing the Aiea-Pearl City region. For this campaign, he pulled together a broad-based coalition of supporters that included military veterans, environmentalists, unions and so-called “progressives.”

Takai was an All-American high school swimmer and University of Hawaii student leader. His military background garnered early support from veteran groups and Illinois U.S. Rep. Tammy Duckworth, a former UH student senate colleague and fellow Iraq War veteran.

Kim, 62, who is known as a scrapper from Kalihi, has held various elected state and city offices since 1982. Her supporters included the women’s right group Emily’s List and blue-collar union powerhouses the United Public Workers and the International Longshore and Warehouse Union.

After the first vote counts were announced, Kim told Hawaii News Now “a lot of outside money that came into the race” during the last three weeks of the campaign may have factored in the election results.

As the primary election neared, Takai got a boost when Votevets.org ran $175,000 in television commercials that described him as the natural successor to late U.S. Sens. Daniel K. Inouye and Spark Matsunaga, both decorated World War II veterans.

The same organization spent $300,000 in super PAC money in support of U.S. Rep. Tulsi Gabbard in her surprisingly easy victory over then-Honolulu Mayor Mufi Hannemann in the 2012 2nd Congressional District Democratic primary.

Later, in a statement, Kim pledged to support Takai in the general election.

The 1st Congressional District was left to an open field after Democratic U.S. Rep. Colleen Hanabusa chose to challenge U.S. Sen. Brian Schatz in his bid for a full term after being tapped to take over for Inouye when the senior politician died in December 2012.

Chang and Takai both chose to forgo re-election bids to seek the congressional seat, so Chang will be out of a job come January.

Kim, Anderson, Espero and Manahan are in the middle of four-year terms and will continue in their current elected posts.

Djou easily won the GOP primary over opponent Allan Levene Saturday, collecting more than 90 percent of votes. Djou has stressed to voters that he would be an independent voice for Hawaii in Congress.

Neither nonpartisan candidate in the race, Calvin Griffin and Robert H. Meyer, appeared to have enough votes to meet the threshold to make it onto the general election ballot.

In the 2nd Congressional District, Gabbard ran unopposed in the Democratic primary. Republican Kawika Crowley, who lost to Gabbard in the 2012 general election, won 43 percent of votes, beating out Marissa Capelouto at 32.5 percent. Libertarian Joe Ken ran unopposed.