As the debate between Democratic U.S. Senate candidates showed Thursday night, fighting a dirty campaign can backfire big time, doing more damage to a candidate’s long-term goals than win him support.

During the debate broadcast live on PBS stations throughout Florida, Peter Deutsch continued his tactic of tying Betty Castor to former USF engineering and computer science professor Sami al-Arian, who was arrested in February 2003 and is under suspicion for allegedly supporting terrorist organizations. Deutsch asserted throughout his campaign that Castor had not handled al-Arian correctly while she was USF president. Even though Castor received information from the FBI that cleared the former USF professor from suspicions at the time, Deutsch kept harping on the topic.

Audience reaction at the studio when Deutsch continued bickering with Castor gave the indication that Deutsch was hurting himself more than he was Castor. Alex Penelas, also a contender for the Democratic ticket in the bid for the Senate seat Democrat Bob Graham will vacate when he retires at the end of this term, agreed with the audience. “We need to stop the bickering,” Penelas said. “There are too many important issues facing America,” such as health care and the situation in Iraq. Such topics should be the focus of the debates, he continued, “not tearing each other apart.”

Deutsch nevertheless refused to stop airing campaign ads that focus on Castor’s involvement in the al-Arian affair, which he categorized as not at all “critical” or negative but “absolutely factual.”

Campaigns that focus on negativity are by no means rare. In 2000 President George W. Bush, for example defeated fellow Republican Sen. John McCain in his bid for the presidency by suggesting McCain was unpatriotic. The fact that the senator had spent several years as prisoner of war in Vietnam, where he was tortured regularly, while Bush still cannot prove conclusively that he even served National Guard duty in Texas did not seem to stop such tactics.

Like the presidential campaign, in which Bush now banks on support from the man whose integrity he once questioned, Deutsch’s actions hurt his party’s interests in the long run. While it looks like Castor will come out on top in next week’s primary, the seed of doubt has been planted among voters. Even though it is no doubt in Deutsch’s interests to have a member of his own party elected to the U.S. Senate rather than a Republican, he is actively hurting his party’s efforts to retake a majority in the Senate.