A campaign ad in a bitter Tennessee senate race that took a swipe at Canada has been pulled, though a Republican Party spokesperson said Wednesday the decision had nothing to do with the controversy it had generated on both sides of the border.

The race between Republican Bob Corker and Democrat Harold Ford Jr. is seen as key to helping determine which party takes control of the Senate come Nov. 7. The battle has led to a series of allegations and counterattacks in campaign ads and on political talk shows in the U.S.

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Democratic Senate nominee Harold Ford Jr. is looking to represent Tennessee in the U.S. Senate after five terms as a congressman. ((Mark Humphrey/Associated Press))

Actors in one "man on the street" ad take turns as apologists for Ford's alleged shortcomings in policy and in character, with one expressing the view that Democrats andCanada are both soft on the issue of global security.

"Canada can take care of North Korea," the man in the ad says. "They're not busy."

A Canadian government source told the Canadian Press that ambassador to Washington Michael Wilson had expressed concerns on behalf of the Conservatives to a White House official.

Liberal MP Omar Alghabra took up the issue in question period on Wednesday.

"Is this what Canadians should be expecting as the outcome of cozying up to Mr. Bush by the prime minister and his Conservatives?" said Alghabra.

"I have a question for the prime minister. Will he call his mentor, President Bush, and demand this insulting ad be pulled from the airwaves immediately, and stand up for Canada, but for real this time?"

Canadian officials were not the only ones with objections.

In the same ad, a blonde woman claims she met Ford, an African-American, at a Playboy party and beckons the candidate to "call me."

The National Association for the Advancement of Colored People categorized the ad in a statement as "a powerful innuendo that plays to pre-existing prejudices about African-American men and white women."

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Republican U.S. Senate candidate Bob Corker called a controversial campaign ad directed at his opponent 'tacky.' ((Tom Sherlin/Associated Press/The Daily Times))

Fordhas denied ever having been to the Playboy mansion in California, but admits being at a 2005 Super Bowlparty in host city Jacksonville, Fla., which was hosted by Playboy and attended by about 3,000 people.

The same ad also alleges that Ford took money from porn movie producers.

'Run its course'

A Republican NationalCommittee official told NBC the ad had been pulled because it had "run its course," just one day after party chairman Ken Mehlman defended the ad and said it would continue to run.

Corker's team had said the ad had been created by a third party, though the candidate said it was "tacky" and "not reflective of the campaign we are running."

Yet another ad, however, takes aim at Ford's pro-choice stance, alleging "[Ford] wants to give the abortion pill to our schoolchildren."

Corker is the one-time mayor of Chattanooga, while Ford is in his fifth term in the U.S. house.

They are competing for the vacant seat previously held by Republican Bill Frist, who is believed to be mulling a run for presidential nominee in 2008.

With files from the Canadian Press