WASHINGTON — Herman Cain, the Republican presidential candidate with the sharp wit and easy-to-remember tax plan, is a cancer survivor, radio host and former chief executive of Godfather’s Pizza. On the campaign trail, he talks up his business experience, casting himself as a “problem solver” and Washington outsider.

But the role that helped propel Mr. Cain into politics was that of an ultimate Washington insider: industry lobbyist.

From 1996, when he left the pizza company, until 1999, Mr. Cain ran the National Restaurant Association, a once-sleepy trade group that he transformed into a lobbying powerhouse. He allied himself closely with cigarette makers fighting restaurant smoking bans, spoke out against lowering blood-alcohol limits as a way to prevent drunken driving, fought an increase in the minimum wage and opposed a patients’ bill of rights — all in keeping with the interests of the industry he represented.

It was a role that gave him an intimate view of the way Washington works, putting him in close proximity to Republican leaders at the time, including Newt Gingrich, now one of his presidential rivals, and John A. Boehner, now speaker of the House. And it helped Mr. Cain lay the groundwork for the next chapter in his life, his entry into electoral politics, beginning with a short-lived bid for the White House in 2000.