The race for the Republican presidential nomination in the U.S. was shaken up Thursday, with Texas governor Rick Perry ending his campaign two days ahead of the South Carolina primary election. He strongly endorsed one of the remaining contenders, former House of Representatives Speaker Newt Gingrich.

Pre-election surveys showed Perry trailing among five contenders in South Carolina. But his endorsement of Gingrich could help him overtake the party's presumed front-runner, Mitt Romney, a one-time venture capitalist and former governor of Massachusetts viewed by some Republicans as not ideologically conservative enough.

At a parting news conference, Perry said Gingrich has “the ability to captivate conservatives” in their attempt to oust President Barack Obama, a Democrat, in next November's national election. Perry acknowledged that he has had his differences with Gingrich, but added, “Newt's not perfect, but who among us is?”

Surveys in South Carolina show Gingrich gaining fast on Romney, even as numerous U.S. political analysts view Romney as the party's eventual nominee.

Hours before Perry dropped out of contention, Republican officials in the state of Iowa said a third candidate, Rick Santorum, a former senator from Pennsylvania, captured the most votes in the state's January 3 caucuses, not Romney.

Initially, Iowa Republican officials said that Romney unofficially won the caucuses by eight votes, and Santorum came in second.

But after certifying the votes, Iowa party officials on Thursday said Santorum finished with 34 more votes than Romney. However, they did not declare Santorum the official winner because vote tallies from eight caucus gatherings are missing and will never be recovered.

The changed vote total could give Santorum, a social conservative opposed to abortion and same-sex marriage, a boost against both Romney and Gingrich. The three candidates, and the fourth one remaining in the race, Texas congressman Ron Paul, are set to debate again Thursday night.

Perry led the chase for the Republican nomination at one point, shortly after he entered the race last August. As the long-time governor of one of the country's largest states, he touted his conservative views and his record of creating jobs at a time when the sluggish performance of the national economy is at the forefront of many voters' minds.

But he stumbled badly in debates with the other Republican contenders, at one time failing to remember one of the three federal agencies he wanted to eliminate. Failing to recall the third agency, he simply said, “Oops.”

His brain freeze and “oops” comment quickly became a punchline for the country's television comedians.