U.S. Sen.-designate Brian Schatz left for Washington aboard Air Force One tonight after he was selected by Gov. Neil Abercrombie to replace the late U.S. Sen. Daniel Inouye.

Schatz, 40, will be sworn in Thursday so he can participate in Senate votes to avert a fiscal cliff of federal tax increases and spending cuts scheduled to take effect in January.

President Barack Obama cut short his annual Oahu vacation to work on the budget and other issues when Congress returns Thursday. He invited Schatz to join him on the flight, the White House said.

Schatz said he is “humbled” and “honored” by the appointment.

He said the first thing he would do is reach out to the rest of the delegation to establish Hawaii’s game plan for the coming Congress.

Schatz said he would also reach out to U.S. Senate Majority Leader Harry Reid, D-Nev., and to the White House on the pressing issues now before Congress.

“I am honored to serve in this capacity. … If given the opportunity, I’ll make Hawaii proud,”    Schatz said.

Next in line to be lieutenant governor is Senate President Shan Tsutsui of Maui. Abercrombie said Tsutsui is weighing it and must make a decision “promptly.”          

Schatz, a former Makiki state lawmaker and Democratic Party of Hawaii chairman, was elected lieutenant governor in 2010.

Abercrombie chose Schatz from a list of recommendations from the Democratic Party of Hawaii that included U.S. Rep. Colleen Hanabusa and and Esther Kiaaina, the deputy director of the state Department of Land and Natural Resources.

Inouye had asked Abercrombie to name Hanabusa, who represents urban Honolulu’s 1st Congressional District, as his “last wish” before he died last week at 88 of respiratory complications.

Jennifer Sabas, Inouye’s chief of staff, issued a statement, saying, “Sen. Inouye conveyed his final wish to Gov. Abercrombie. While we are very disappointed that it was not honored, it was the governor’s decision to make. We wish Brian Schatz the best of luck.” 

Hanabusa congratulated Schatz and said she “will continue to work to serve the people of our state, and support our delegation’s efforts.”

“Having served as chair of the Hawaii Senate Judiciary Committee when the succession law was passed, I fully respect the process and the governor’s right to appoint a successor,” Hanabusa said in a news release. 

Schatz will become the state’s senior senator. U.S. Rep. Mazie Hirono, who was elected in November to replace the retiring U.S. Sen. Daniel Akaka, would be the junior senator.

Schatz will serve until voters in 2014 elect a senator to fill out the remainder of Inouye’s six-year term, which runs through 2016. Schatz said he plans to run in 2014 and in 2016.

Schatz will be the youngest U.S. senator — for a few days. Mike Lee of Utah and Marco Rubio of Florida, both 41, are currently the youngest. Sen.-elect Chris Murphy of Connecticut will become the youngest at 39 when he is sworn in Jan. 3.

Inouye died Dec. 17 at 88 of respiratory complications.

The Democratic Party of Hawaii’s state central committee heard from more than a dozen candidates this morning at the party’s headquarters at Ward Warehouse before going into private executive session to come up with the short list.

Prior to Abercrombie’s announcement, Hanabusa said in a video message from Washington D.C. that she is honored to have the senator’s support but respects that it is the state central committee and the governor that will make the selection.

“Not one of us has any favorable rights to that position,” she said. “Having said that, I also ask that each and every one of you consider what we are facing in Washington, D.C., and what his successor must be able to do. The most critical thing is they must be able to hit that ground running.

“We are being faced with major issues, the stability or our nation and our state is at risk. We are looking at the fiscal cliff. We are also looking at another debt ceiling debacle with the Republicans. And I believe that I have the qualifications to best address those concerns.”

Schatz said that while no one could fill Inouye’s shoes, he has the potential, because of his youth, to build up seniority over decades if he is appointed and supported by Democrats for election in 2014 and 2016.

“I want to be your senator because Hawaii’s values need to be represented on the national stage, that compassion and a love of peace is a sign of strength, not of weakness, and that we can disagree without being disagreeable,” he said.

U.S. Rep.-elect Tulsi Gabbard, who would be the first woman military veteran to serve in the Senate, also had applied for the seat. She said she has already made national connections since her November election that could be helpful to the islands.

“We’re facing desperate times,” she said. “Our new senators will have little power and no real seniority for at least 15 years. How can we solve this problem? We need someone in the U.S. Senate who will not only build seniority over time, but will immediately have influence and be effective despite the lack of seniority.”

The state central committee, which allowed the public and the news media to witness the candidates’ remarks, also heard from candidates former congressman Ed Case, state Senate Vice President Donna Mercado Kim, state Sen. Will Espero, Abercrombie deputy chief of staff Blake Oshiro and Oahu Democratic chairman and labor attorney Tony Gill.