Annoyed that Newt Gingrich snubbed his achievement inlast week's eleventh-hour auto deal with Japan, Trade Representative Mickey Kantor is challenging the House Speaker to a debate. Wednesday,Gingrich dismissed Kantor's confrontational strategywith Japan as "insane" and suggested more low-key trade barriers -- say, inspecting all Japanese cars at a checkpoint in Seattle. "If the speaker believes that the last 40 years have been acceptable and that we shouldn't insist on a level playing field with the Japanese, I would be prepared to debate him -- anywhere, anytime," Kantor fired back today. Gingrich had no immediate response. Left off the tag team: Senate Majority Leader Bob Dole, who has called the trade agreement "virtually empty" and impossible to enforce.