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Texas Governor Rick Perry has announced he will not seek a fourth term in office next year.

The 63-year-old Republican, who is the state's longest-serving governor, said at a news conference in San Antonio that he planned to retire.

He has built a reputation as a job creator, and as a defender of Christian conservative values and states' rights.

But he will also be remembered for forgetting one of his own policies at a 2011 presidential debate.

Media playback is unsupported on your device Media caption Rick Perry famous "brain freeze" moment

Gov Perry was briefly the front-runner in the Republican race for the White House when he entered the fray in August that year.

But his candidacy disintegrated spectacularly after he muttered "oops" as he forgot the third of three federal departments he had pledged to close, while debating with his rivals live on television.

Gov Perry later endorsed the eventual nominee, Mitt Romney, who failed in his attempt to derail Democratic President Barack Obama's bid for a second term.

Gov Perry's announcment on Monday that he would retire has sparked speculation that Texas Attorney General Greg Abbott may run to replace him.