The sixth Republican debate kicked off Tuesday in Dearborn, Mich., with nine GOP presidential hopefuls taking the stage.Fred Thompson made his debate debut of the Republican presidential campaign, and said that while the economy is strong, the government is "spending money of future generations and those yet to be born."The former Tennessee senator and actor said, "We are spending money we don't have," but he advocated no changes to shift course. By coincidence or design, Thompson drew the first question of a two-hour debate devoted to the economy. It was the sixth debate of the campaign for the White House, and the first one since he announced his candidacy several weeks ago.The CNBC/MSNBC/Wall Street Journal debate is also the first of the 2008 campaign to focus on economic issues.