THE CAMPAIGN FOR THE DFL NOMINATION FOR GOVERNOR IS IN ITS FINAL WEEK AND THE MISSION IS CLEAR FOR FRONT RUNNER SKIP HUMPHREY: WITHSTAND A WEEK OF ATTACKS FROM HIS 4 CHALLENGERS. MINNESOTA PUBLIC RADIO POLITICAL EDITOR BOB COLLINS HAS THAT AND MORE IN TODAY'S POLITICAL ROUNDUP. ANY QUESTION THAT THE DEMOCRATS HAVE DROPPED THEIR INFORMAL AGREEMENT TO BE RELATIVELY NICE TO EACH OTHER DURING THE PRIMARY CAMPAIGN HAS VANISHED IN THE LAST FEW DAYS. IN LAST NIGHT'S DEBATE ON THE MINNESOTA NEWS NETWORK, VIRTUALLY EVERY CANDIDATE WITH THE EXCEPTION OF MARK DAYTON, AIMED THEIR RHETORIC AT SKIP HUMPHREY.