As a politician, Duncan took positions which placed him in the progressive or moderate wing of the Oregon Republican Party, as were many of his immediate predecessors and contemporaries, including the likes of Tom McCall, Clay Myers, Bob Packwood and Mark Hatfield. He supported the creation of Metro, voted for Governor Kitzhaber's transportation package, and was on record as pro-choice and in favor of nondiscrimination laws for gays, prompting "Willamette Week" to characterize him as "a moderate's moderate," in its 1998 editorial endorsement.