On Dec. 18, a letter from Sen. Daniel Inouye was hand-delivered to Hawaii Gov. Neil Abercrombie. It read, in conclusion: “I hope you will grant me my last wish.” It was dated Dec. 17, 2012, the day of Inouye’s death.

In Inouye’s absence, Abercrombie had just become the titular head of the Democratic Party in Hawaii. And he had a critical decision to make: Whom to appoint to replace the popular U.S. senator.

For years, Inouye had groomed Rep. Colleen Hanabusa to succeed him, since she had caught his eye as the first woman president of Hawaii’s Senate, and then when she won a seat in Congress in 2011.

Just a few weeks before Inouye was hospitalized, he and Hanabusa lunched in Washington, D.C., and talked about how she might succeed him. Inouye planned to retire in 2016, and he and Hanabusa planned for her to run for his seat.

Then illness scuttled his timetable.

“Colleen possesses the intellect, presence and legislative skill to succeed in the Senate,” Inouye wrote to Abercrombie in the letter he dictated from his deathbed. “I have no doubt that she will represent Hawaii with the same fervor and commitment that I brought to the Senate chamber since 1962.”

Irene Hirano Inouye, the late senator’s widow, expected he would appoint Hanabusa, but a few days later, Abercrombie pulled a stunner: he picked his lieutenant governor, Brian Schatz, to take Inouye’s place, putting the governor’s stamp on the symbolic Senate seat, and all but ensuring a heated primary in 2014.

The seat is firmly Democratic, and so the victor in the primary race, either Schatz or Hanabusa, will likely coast on to win the general election.

Schatz, although boasting a few months’ incumbency, is aware of his vulnerability and has been raising money and mining endorsements frenetically: He finished the second quarter with more than $1.6 million and recently touted an endorsement from former Vice President Al Gore.

Hanabusa, who announced in May that she would challenge Schatz, ended the quarter with more than $653,000. She has been backed by former Sen. Daniel Akaka, who also made a call to the governor on her behalf when Inouye died, and EMILY’S List, the liberal outside group.

Polls for the race so far have been inconclusive.

Distilled, the primary is a contest between two distinct political personalities — not those of the candidates themselves, who are in most ways remarkably similar, but of their allies and mentors: Abercrombie, a boisterous, one-time hippie, and Inouye, a quiet, traditional war hero.

Inouye had to petition to fight during World War II, at a time when the U.S. government was actively marginalizing and interning Japanese Americans. He lost an arm on an Italian battlefield, where he continued to lob grenades at enemy combatants, and he was awarded the Medal of Honor in recognition of his heroism.

The other half of his mythology is his decades in Congress, where he was the first Asian-American senator and, later, chairman of the Appropriations Committee and a master of earmarks. At home, he was the kingmaker and godfather of the Hawaii Democratic Party: He picked the winners and, in so doing, guaranteed they would win.

Inouye knew his decisions mattered and so didn’t come by them easily. But he was sure about Hanabusa.

“’She could do what I do.’ That’s what he would say,” said a former aide, who now works for Hanabusa.

If Inouye represented the old guard of Hawaiian politics, Abercrombie has embodied the opposite. He decamped to the islands as a post-grad student from Buffalo, N.Y., just as Hawaii was navigating its first few years of statehood. He almost immediately tried his hand in politics — first in a failed bid for the U.S. Senate, in which his anti-war platform and yellow checkered taxi became his early trademarks.

The long-bearded mainlander might have struck islanders as antithetical to traditional Hawaii politics, but his gregariousness won voters over. In 1986, after getting his start in the statehouse, Abercrombie won a seat in Congress — where he found himself serving on the same congressional delegation as Inouye. The two men worked together, but they did not find common ground personally.

When Abercrombie won the race for governor in 2010, with Schatz as his lieutenant, some Democrats sensed a latent power struggle between Abercrombie and Inouye.

It is bubbling up now, by proxy, between Schatz and Hanabusa.

Their careers have been nearly parallel: Both were elected to the statehouse in 1998, and each won a higher office in 2010.

But they have often found themselves on polar ends of the Hawaii Democratic sphere. When Hanabusa and Inouye worked together to boost Hillary Clinton during the 2008 Democratic primary in Hawaii, Schatz headed up efforts on behalf of Obama.

In the pronounced ethnic divide that is unique to Hawaii, Schatz, who is Caucasian and a transplant, and Hanabusa, Japanese-American and born in Hawaii, each has a distinct demographic advantage.

The two lawmakers have even faced each other in a primary once before: in the 2006 Democratic contest for the second congressional district seat. Both lost — Hanabusa by less than 1 percent, Schatz by more than 12 points — to now-Sen. Mazie Hirono, who does not plan to endorse a candidate in the Senate primary, an aide said.

As they vie for a Senate seat, Schatz and Hanabusa will be trying to move out of their patrons’ shadows. It will be a particular challenge for Hanabusa, who will seek to remind voters of Inouye’s support for her while stressing her independent achievements.

“It’s not that we’re inextricably linked,” she said in an interview last week. “People know me in my own light as well.”

Inouye’s last-breath endorsement, she said, is “more like an enhancement than anything else.”

Schatz, who declined to comment, will face his own iteration of the problem. Hanabusa’s allies will attempt to portray him as “Abercrombie’s senator.” He will seek to dispute that — while touting the governor’s support.

And he, too, will need to talk about Inouye, because Hawaiians haven’t stopped.

Whenever she’s home, Hanabusa said, people approach her regularly to talk about the late senator. They stop her in the grocery store, so often and for conversations so lengthy that her husband now stays home.

“Most of their regret is, ‘I never got to say thank you, never got to give him a hug,’” Hanabusa said.

The extent to which Inouye’s ghost will guide the direction of the Democratic Party and the state is an open question. It will be answered in no small part by this primary.

“When Sen. Inouye was alive, there were parts of our party that were not happy, but there was at least some order,” said Jennifer Sabas, who worked as his chief of staff for 25 years and is now advising Hanabusa’s campaign. “These are very tumultuous times. Not bad, just different, as different groups and leaders are looking for their time in the sun.”