The live telephone survey found Clinton, the former secretary of State, leading Trump, the celebrity billionaire, 35.1 percent to 33.5 percent among likely voters in the traditional red state, well within the poll’s margin of error of plus or minus 3.3 percentage points.

Third-party candidates captured another 8 percent or so: Libertarian Gary Johnson was supported by 6.9 percent; Green Party nominee Jill Stein by 1.5 percent.

Another 22.9 percent haven’t decided yet.

Because people were asked concretely about what they plan to do, the poll got to the heart of how many Arizonans are undecided about the presidential race, said Eric Hedberg, director of research for the Morrison Institute for Public Policy. “I think that’s the big finding: There’s still the 20 percent out there who haven’t made up their minds.”