Sen. John Kerry has canceled his visit to Philadelphia Wednesday night.

Kerry was supposed to appear at the Public House on Arch Street to campaign for Pennsylvania Senator hopeful Democrat Bob Casey Wednesday night.

The cancellation comes amid some controversial comments made by the Democratic senator. Kerry and the White House are now engaged in a war of words.

President George W. Bush said Kerry insulted U.S. troops by telling students to study hard or they might "get stuck in Iraq."

"The senator's suggestion that the men and women of our military are somehow uneducated is insulting and shameful," Bush said. "The men and women who serve in our all-volunteer armed forces are plenty smart and are serving because they are patriots -- and Sen. Kerry owes them an apology."

Kerry said he misspoke and his comment was aimed at the Bush administration.

The Casey campaign confirmed that Kerry would not appear at the rally. In a story published Wednesday in The Philadelphia Inquirer, Casey said it appeared Kerry "botched a joke."

"That's what he said, and I take him at his word," Casey said. "He served in combat. Last time I checked, the president and the vice president did not. The White House and the Santorum forces should get to work on dealing with the real problems in Iraq."

Kerry retaliated to Bush's criticism and said the attack was similar to the swift boat ads he faced during his unsuccessful bid in the 2004 presidential election.

"We made a decision not to allow the Republican hate machine to use Democratic House candidates as proxies in their distorted spin war in which once again they're willing to exploit brave American troops,” Kerry spokesperson David Wade said. "We've canceled campaign events in Pennsylvania today as well as for House candidates in Minnesota and Iowa today and tomorrow."

He told the talk show host Don Imus that he was returning to Washington D.C. to deal with the issue.

Casey's Republican opponent, Sen. Rick Santorum, had said Casey should disavow Kerry's comments, arguing they are disparaging to troops.

With less than a week to go before the Tuesday general election, Santorum had press conferences planned Wednesday in Wilkes-Barre and Harrisburg to highlight his record on border security and child safety. He also planned to attend a rally in Philadelphia.

Casey had several events scheduled in Philadelphia and made a campaign stop in the morning in Allentown.

Two independent polls released Wednesday showed Santorum continuing to trail Casey, the state treasurer, by double digits.