Little over a month after being elected to serve six years in the senate, Bob Carr has quit politics, saying he was too exuberant when he pledged to see out the full term.
Following Labor's election defeat, Senator Carr decided it was time to move on.
He previously indicated he would stay for the full term, but said in retrospect perhaps the commitment was a moment of "irrational exuberance."
"I was very high spirited about taking this job, but my enthusiasm probably got ahead of a more calculated approach," he said.
The former foreign minister on Wednesday ended weeks of speculation by confirming he would submit his resignation just 18 months after entering the upper house to fill the vacancy left by the departure of Mark Arbib.
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"Hogging the shadow ministry, denying a younger colleague the opportunity to serve in that role I didn't think upon reflection would be in the interests of the Australian Labor Party," he said.
Senator Carr headed Labor's upper house ticket for NSW in the September federal election, and would have started a six-year term from July next year.
His vacant Senate spot is being circled by a number of potential candidates, including former Labor MPs Mike Kelly and Deborah O'Neill who lost their lower house seats at the September poll.
Senator Carr advocated the flexibility of bringing in an outsider for the casual vacancy his resignation creates, just like his elevation to foreign minister by Julia Gillard in March 2012.
But he said he had no influence over who would take his spot, and didn't think it proper to speculate.
"I think it's bad form for someone vacating a position to baptise a successor," he said.
Senator Carr vowed not to dwell on the politics of his beloved Labor Party but instead reinvent himself as an academic after announcing he is quitting the Senate.
He will take up two teaching appointments at Sydney-based universities, where he will focus on Asia, China and international relations.
He would not dwell on the past by becoming "one of those creatures" commenting on machinations of the Labor Party.
He said it was a "very great honour" to serve as foreign minister, describing it as an unrivalled learning experience "equivalent to a dozen PhDs".
He cited achieving closer ties with Myanmar and the Arab world as among his best accomplishments, as well as Australia winning its bid for a seat at the UN Security Council.
With a nod to both prime ministers he worked under, Senator Carr said adieu.
"With malice towards none, and generosity and charity to all, I bid my farewell," he said.
Labor leader Bill Shorten thanked Senator Carr for his service as foreign minister and his broader contribution to the ALP.
"There are few people who have dedicated such time and commitment to public life and the labour movement as Bob Carr," Mr Shorten said in a statement.
"Senator Carr's list of achievements in public life are extraordinary."
