Tim Pawlenty and Ron Paul are officially presidential candidates.

Both formed "exploratory committees" in the previous month and a half, for the purpose of exploring the possibilities of candidacy.

Both have filed for presidential candidacy in South Carolina -- a requirement for participating in the first GOP primary debate of the 2012 election cycle, cohosted in Greenville, S.C., by Fox News and the South Carolina Republican Party.

And both candidates were aware that, by doing so, they have officially become presidential candidates in the eyes of the law. Spokesmen for both Pawlenty and Paul acknowledged that filing for candidacy in South Carolina changes their bosses' status in the eyes of the Federal Election Commission.

In the so-called "exploratory phase" before officially launching a campaign, Pawlenty and Paul have been "testing the waters" of candidacy, as FEC regulations categorize it. They can raise money and travel the country for the purpose of determining whether to run. During this time, they have not been required to disclose their finances to the FEC.

Now that they've filed for candidacy, that will change. As the FEC specifies, an individual is no longer "testing the waters" when he/she "takes action to qualify for the ballot" or meets several other criteria. At that point, he/she becomes a bona fide presidential candidate -- as Pawlenty and Paul have.

That doesn't necessarily mean they'll carry their campaigns forward, say spokesmen, and neither candidate is ready to make a formal announcement just yet.

"Dr. Paul still has not made a final decision, but he is serious enough to invest $25,000 to keep the door open," said Paul adviser Jesse Benton, referencing South Carolina's $25,000 filing fee.

"He'll have a formal and final announcement in coming weeks," said Pawlenty spokesman Alex Conant. "The filing was required now to participate in the debate."

Presumably, the debate's other participants are now candidates in the eyes of the law, as well. Former senator Rick Santorum (R-Pa.), Godfather's Pizza CEO Herman Cain, and former New Mexico governor Gary Johnson (R) are also participating, and have presumably also paid the $25,000 and filed for candidacy. While Santorum has been funded by an exploratory committee, Johnson has already announced he is running for president and is actively campaigning.

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