CNN's Lou Dobbs, a lightning rod for criticism following his transition from a business journalist to an opinionated anchor on such issues as illegal immigration, told viewers Wednesday that he was quitting his nightly show to pursue new opportunities. “This will be my last broadcast,” Dobbs said after giving the day's headlines. Dobbs, who hosts a daily radio show unrelated to CNN, said the network had allowed him to be released early from his contract. Dobbs was a CNN original, signing on when the cable network started in 1980. For much of his time on CNN, he hosted a nightly business broadcast that became one of the most influential shows in the corporate world, and CNN's most profitable show for advertising revenue. But Dobbs said his world view changed after the 2001 terrorist attacks and corporate corruption scandals, and he began to more freely express his opinions. He was particularly persistent in bringing the immigration issue to the fore, winning him both higher ratings and enemies. His presence lately became awkward for CNN.