In what has to be one of the most momentous primary elections in recent Hawaii history, voters are confronted with a difficult choice between two eminently qualified candidates for a U.S. Senate seat.

Although both clearly possess the intellect and political savvy to serve the state well, the Star-Advertiser endorses Brian Schatz, who has held the seat since his appointment in 2012, for the Democratic nomination. In that short time, the 41-year-old former lieutenant governor and state lawmaker has demonstrated a commitment to his party’s ideals and an ability to connect with D.C. power-brokers who can advance a progressive agenda on the state’s behalf.

Absentee mail-in voting is already beginning for the Aug. 9 primary, and one of the hottest races pits Schatz against U.S. Rep. Colleen Hanabusa, who accrued a remarkable record before her own election to the U.S. House in 2010.

Whoever wins the primary will face opposition in the general but, in Hawaii’s solidly blue partisan arena, the Democratic primary is the real knock-down, drag-out fight.

The winner of this race will go on to the general. Cam Cavasso, a former Hawaii lawmaker and businessman, is the only Republican with experience in elected office and deserves the GOP nomination. Cavas-so is an Army veteran, a financial adviser and owner of a contracting firm whose conservative fiscal and social positions will appeal to the party faithful. Rounding out the general-election ballot will be Libertarian Michael Kokoski and whichever nonpartisan finishes on top, Joy Allison or Arturo Reyes.

Hanabusa, 63, in 2006 became the first woman to be elected president of the state Senate, where she represented Waianae’s 21st District from 1998 to 2010. Throughout the campaign she has touted her legislative leadership record among her chief credentials for advancing to the U.S. Senate.

However important political experience may be, though, that’s not the only element from a resume that should come to the fore.

Schatz logged eight years in the state House, chaired the Hawaii Democratic Party and was elected lieutenant governor in 2010 before Gov. Neil Abercrombie tapped him to fill the Senate vacancy left with the death of Daniel K. Inouye.

But Schatz also led Helping Hands Hawaii, one of the state’s largest nonprofit organizations catering to the needs of poor families and individuals, from 2002 to 2010. His investment in community service goes back further, to 1994, when he co-founded another nonprofit, Youth for Environmental Service. Democratic voters evaluating a candidate’s allegiance to core party values ought to count those entries on Schatz’ side of the ledger.

Many have characterized his rise to the U.S. Senate as an uncommonly lucky break; that’s undeniably true. Hanabusa was widely known as Inouye’s choice as a successor, and the fact that Schatz vaulted to the delegation’s senior Senate seat — even ahead of his colleague in the chamber, Mazie Hirono — undoubtedly set teeth on edge among the Democratic Party old guard.

Once he got to Washington, though, Schatz got to work earning his keep. In short order, he was given the chairmanship of two new Senate panels convened on topics that matter greatly to Hawaii.

The Subcommittee on Tourism, Innovation, and Competitiveness has drawn Hawaii industry leaders to two hearings so far. And for a state with a longstanding pledge to boost clean energy, chairing the Subcommittee on Water and Power is a fortuitous position, too.

He has managed to secure appropriations such as funding critical to the East-West Center, the rail project and defense.

Yes, it’s easier to score points as a member of the Senate’s majority party; Hanabusa had no such circumstance in the House. But if Schatz was handed the ball, he’s done a capable job running with it, readily forging important relationships.

On most national policy issues, Schatz aligns well with his party positions. He collaborated on legislation promoting college affordability, universal preschool and other planks from the Democratic platform.

Hanabusa has been an outspoken opponent of further military entanglements — in Iraq, particularly — and that’s the right instinct. However, in last week’s final debate, she suggested that the White House consider withdrawing its diplomats rather than sending in troops to protect them.

Schatz, who presents the more nuanced view of defense policy in general, rightly pointed out the embassy is the entry point to engaging in diplomacy, which offers the only possibility of a solution. He also seems more willing to challenge assumptions about the military footprint in Hawaii, pledging to first seek residents’ views on proposals to expand activity at Hawaii island’s Pohakuloa Training Area.

Much has been made over the course of the campaign about his relative youth. His age matters less, in and of itself, than the fact that he represents a fresh perspective this state needs in its leadership. Schatz brings experience, idealism and vision to the job of shaping a future that his own children’s generation will inherit.

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