After expressing interest in running for the White House in 2008, Sen. Rick Santorum (Pa.) said Monday he has no plans to seek the Republican presidential nomination.

Hours after making the declaration, Santorum’s aides stressed this was not a Shermanesque statement and claimed the Pennsylvania Senator has not entirely closed the door on a White House run.

Santorum caused a minor stir Monday afternoon on Capitol Hill when he suggested during a washingtonpost.com online discussion that a 2008 presidential campaign was unlikely.

“I have six children ages 4-14. And the idea of coming off a race of the intensity that I am engaged in at this point and turning around and running another two year campaign for president is not something that I believe is in the best interest of my family, which I say in the book, and I believe in my heart it’s my principal responsibility,” Santorum said in response to a question about politicians political aspirations. “I can’t speak for other politicians but I can speak for me, and my intention is not to run in 2008.”

The Pennsylvania Senator participated in the live chat to promote his new book, “It Takes a Family.”

Ever since Santorum expressed interest in seeking the Republican presidential nomination in 2008, he has noted that his family obligations would weigh heavily on such a decision. Robert Traynham, Santorum’s communications director, echoed this sentiment Monday afternoon but would not close the door entirely on a 2008 bid.

“Sen. Santorum has stated on more than once occasion that his first priority is his family,” Traynham said of Santorum, whose term is up in 2006. “He looks forward to a spirited race for re-election to the United States Senate, and he has no plans on putting his family through another campaign.”

But Traynham added, “The Senator believes and has always said, ‘Never say never in respect to running for higher office.’”

Before Santorum gives a serious look to the 2008 nomination, though, he must first win reelection to a third term.

Democrats have said that defeating Santorum, chairman of the Republican Conference, next year is one of their top priorities. The Democratic Senatorial Campaign Committee as well as individual Democratic Senators have criticized Santorum in recent weeks for both his personal views and his voting record.

Santorum is likely to face state Treasurer Bob Casey Jr. (D), a pro-abortion rights lawmaker and son of the late Gov. Bob Casey, in 2006. A recent poll conducted by Quinnipiac University shows Casey leading Santorum 50 percent to 39 percent.

Upon hearing Santorum’s latest comments about a possible White House bid, DSCC spokesman Phil Singer quipped, “People in 49 states can breathe a sigh of relief and after November 2006 people in Pennsylvania will be able to do so as well.”

Should Santorum win re-election, the Pennsylvania Senator still intends to run for Republican Whip — the second-highest ranking GOP leadership position in the Senate.

“He plans to not only win re-election next year, but also serve the party as its Republican Majority Whip,” Traynham said.

Santorum is not the only Republican Senator who has been mulling a White House bid. Majority Leader Bill Frist (Tenn.) and Sens. George Allen (Va.), Sam Brownback (Kan.), Chuck Hagel (Neb.) and John McCain (Ariz.) are all said to be weighing runs for the GOP presidential nomination.