HELENA, MT—As Montana's Senate race heats up in its final weeks, Democrat Jon Tester has challenged his opponent, incumbent Republican Conrad Burns, to prove his commitment to his principles and to the people of Montana by dropping out of the race. "You have said time and again, Mr. Burns, that small governments best serve society," said Tester during a speech before a prominent cattle-ranching group Monday. "If you believe what you say, then I challenge you: Prove your convictions by dropping out of this race, or be known as another politician who refuses to live by his word." Burns responded to the challenge by issuing a counter-challenge calling upon his rival to limit all campaign spending from now until election night to zero.