Republican Sen. Dave Durenberger challenged Democratic opponent Hubert H. Humphrey III during a debate Monday night to stop all negative campaign advertising, and Humphrey refused. Durenberger, in his opening statement during the hour-long televised debate at Carleton College here, told Humphrey that Minnesotans don't like nasty ads and are turning off to the candidates because of them. ``Tonight I am taking all my commercials off the air that have any reference to you, and I'm asking you to do the same thing,'' Durenberger said. Humphrey, who has trailed Durenberger by more than 10 percentage points in all recent independent polls, said he won't stop running advertisements that focus on the 10-year veteran senator's record. ``It's important for the people of Minnesota to know the record,'' Humphrey, the state attorney general, responded during the forum sponsored by the League of Women Voters of Minnesota. ``The people of Minnesota, you're going to rehire someone, or you're going to hire someone new,'' Humphrey said. Durenberger said after the debate that he would respond to Humphrey's commercials with paid air time if he has to, but will no longer run ads such as two recent ones that portrayed Humphrey as being soft on crime. Humphrey told reporters, ``Campaigns are on the record ... and I wish this would be a nicer campaign, but frankly his record's not very good for Minnesota.'' Humphrey focused his attacks on a Senate Ethics Committee investigation into comments Durenberger made to supporters in 1987 that the committee determined had the appearance of leaking sensitive national security information. The committee took no action, but Humphrey said it rebuked Durenberger.