The Senate results mirror the presidential race in the state: Democrat Joe Biden holds a 1-to-4-point lead, depending on the turnout model, in the Monmouth survey.

The new public polling underscores that North Carolina remains an uphill battle for Republicans, even as they have centered on the Cunningham affair as a closing message in the race. The National Republican Senatorial Committee, Senate Leadership Fund, a top GOP super PAC, and Tillis' campaign are running TV ads attacking Cunningham for the affair.

The Monmouth survey matches the results of two online polls also showing Cunningham still outpacing Tillis. A SurveyUSA poll conducted for WRAL-TV showed him ahead, 49 percent to 39 percent; a poll from Morning Consult showed him leading, 47 percent to 41 percent.

The challenge for Republicans: Voters already have high awareness of the affair. In the Monmouth survey, 80 percent of voters had heard about Cunningham's texts with a woman who is not his wife. But only 14 percent said it disqualified him from office; 32 percent said it called his character into question but did not disqualify him; and 51 percent said it’s an issue for only him and his family.

Tillis and GOP outside groups have argued Cunningham's affair undermines the central themes of his candidacy — using their ads not to inform voters of the scandal, but to change their minds in the race.

Both Cunningham and Tillis had unfavorable images in the Monmouth survey; Tillis' image was underwater but largely unchanged from August, while Cunningham's image became significantly worse after holding a positive favorability in August.

Monmouth surveyed 500 registered voters from Oct. 8-11, with a margin of error of plus or minus 4.4 percentage points.