Republican Rudy Giuliani went to a hospital Wednesday night for flu-like symptoms, his campaign said.

The former New York City mayor felt the symptoms while campaining for the Republican presidential nomination in Missouri, and they soon became worse, campaign spokeswoman Katie Levinson said. The mayor decided to go to a hospital and spend the night in the city, she said.

"The symptoms worsened as the day wore on and shortly after taking off from Chesterfield, Missouri, for New York the mayor became uncomfortable enough that our plane returned to the airport in Chesterfield," Levinson said. "To be on the safe side, the mayor consulted with his personal physician in New York and made the decision to go to the Barnes Jewish Hospital in St. Louis for routine tests."

Giuliani had no scheduled appointments for Thursday, said his spokesmwoman Maria Comella.

Earlier in the day, Giuliani had used a baseball analogy to explain his reasons for targeting Missouri when other candidates are focused on the early voting states of Iowa and New Hampshire, where Giuliani trails his rivals in polls.

Challenging tradition, Giuliani is devoting more of his attention to the delegate-rich Feb. 5 states — some two dozen including New York, California and New Jersey hold primaries and caucuses that day — while spending limited time in Iowa and New Hampshire.

Missouri, a Feb. 5 state, has gotten little campaign attention but offers 58 delegates, as many as Iowa and New Hampshire combined.

"A baseball game, you've got to play nine innings and whoever gets the most runs at the end of the nine innings wins," he told reporters. "So here, you've got to play in 29 primaries. Nobody's going to win all of them, that's for sure. I think on the Republican or Democratic side, that has never happened in contested primaries with great candidates. They've never won every single primary."

"You recognize the reality that you aren't going to win all of them. You've got to win most of them, and most of them are coming on February 5," he said.

The traditional political strategy is to go for wins in the early voting states and create momentum to propel a candidate to the nomination. In an unorthodox approach, Giuliani is counting on a fluid GOP race and the possibility that no one candidate will emerge from the early voting.

Giuliani's strategy calls for securing victories in states that vote later, beginning with Florida on Jan. 29, and promise huge numbers of delegates to next summer's nominating convention.

The former mayor has been the leader in national polls for much of the year, but recently former Arkansas Gov. Mike Huckabee has challenged Giuliani's standing.

Huckabee's gains have come as Giuliani has faced a spate of bad news, even before his illness.

His longtime friend and former police commissioner, Bernard Kerik, was indicted on federal charges. Then, it was disclosed that as mayor Giuliani billed security expenses to obscure city offices while visiting his current wife as their extramarital affair began. He's also been facing questions anew about his consulting business, Giuliani Partners, whose clients include the Persian Gulf emirate of Qatar.

Airplane trouble delayed Giuliani's later appearance in Columbia, where an overflow crowd of several hundred waited in a hotel ballroom while he was driven across the state.