By Yoree Koh, WSJ.com

UPDATE: U.S. Democratic Rep. Mazie Hirono defeated former Hawaii Gov. Linda Lingle on Tuesday night, according to the Associated Press. Ms. Hirono becomes the Aloha State’s first woman senator as well as the first Japan-born immigrant to be elected to the U.S. Senate.

As Japan’s politicians jockey over when to hold the next general election, one of Japan’s own is on the cusp of making U.S. election history.

Recent polls show Democratic Rep. Mazie Hirono is favored to win the open Senate seat in Hawaii when voters cast their ballots Tuesday. If successful, Ms. Hirono will usher in a wave of firsts. She will be the first Japanese immigrant to be elected senator. She will also be the first Buddhist and Asian-American woman. She will be the first woman senator to represent the Aloha State, and is already the first foreign-born woman of Asian ancestry to be sworn into Congressional office.

The 65-year-old congresswoman was born in Fukushima, the northeastern prefecture where the tsunami-damaged Fukushima Daiichi nuclear plant is located. When she was 8 years old, her mother moved the family to Hawaii. Ms. Hirono once said the immigrant experience and being raised by a single mother in economically difficult circumstances made her a “feisty and focused” lawmaker. She became a naturalized citizen in 1959, the same year Hawaii became a state.

Regardless who wins, Hawaii will get its first woman senator. Ms. Hirono, currently serving her third term in the House of Representatives, is up against former Gov. Linda Lingle, a Republican and long-time political rival to whom Ms. Hirono lost the 2002 gubernatorial race. The two women are chasing the seat opened up by Hawaii’s 88-year-old junior senator, Daniel Akaka, a Democrat. After a 36-year career, Mr. Akaka, the Senate’s only Chinese American, announced his retirement last year.

Scores of Americans of Japanese descent have been elected to public office since World War II. Case in point: If Ms. Hirono wins, both senators from the Aloha State will be of Japanese descent. Senior senator Daniel Inouye, who is also a Democrat, made his own imprint on Asian American history as the first Japanese American to serve in the U.S. House of Representatives and later, the Senate. The 88-year-old Mr. Inouye has been a senator since 1963, making him the second-longest serving senator in U.S. history.

There have been only five Asian American senators until now. Four have represented Hawaii and one has represented California.

But no Japanese-born–or any Asian-born for that matter–has been elected to the Senate. According to the U.S. Senate Historical Office, of 1,931 senators who have been sworn in since 1789, there have been 58 born outside the U.S. Most immigrated from Ireland (16), England (12) and Canada (10). One each came from Cuba, Mexico, Antigua and Sweden. People who have been U.S. citizens for at least nine years are eligible to be senator.

Ms. Hirono is a familiar face among Hawaii’s Democratic establishment. Since returning from the mainland after earning a law degree from Georgetown University, she served for 14 years in the state legislature, eight years as lieutenant governor and is currently in her fifth year in the U.S. House of Representatives. Her one election failure was her bid to become governor in 2002. But it raised her profile, both at home and in Japan. State broadcaster NHK covered her campaign extensively and had plans to televise the 2002 election live, according to a Chicago Tribune story.

Ms. Hirono, whose immigrant story seems to resonate with Hawaii’s diverse voting population, has campaigned fully backing President Barack Obama’s platform, casting her opponent as a Republican lackey. The Hawaiian-born president recently recorded a radio ad for Ms. Hirono, noting that she once worked with his late grandmother, Madelyn Dunham.

“So Mazie isn’t just a reliable partner of mine in Washington; she is part of my ohana at home in Hawaii. Now, I need Mazie’s cooperative style and commitment to middle-class families in the U.S. Senate,” said the president in the ad released Saturday. “Mazie is a nationally recognized leader in early childhood education. A staunch defender of Medicare and Social Security.”

Ms. Lingle’s campaign challenges Ms. Hirono’s past claims of support for the middle class. “Contrary to her rhetoric and her efforts to portray herself as caring about working people, Mazie Hirono’s actions clearly illustrate either that her words are just talk or that she simply does not understand the impact of her votes,” said Retired Maj. Gen. Robert Lee, Ms. Lingle’s campaign manager, in a statement on Oct. 23.

In the final days of campaigning, polls indicated Ms. Hirono breaking away from her opponent with as much as a 22-percentage-point lead.