Iowa Republican Sen. Joni Ernst’s Democratic challenger has a narrow edge on the incumbent six weeks before Election Day, according to a new poll.

Democrat Theresa Greenfield leads Ernst by 3 percentage points in their Senate race among likely voters, 45% to 42%, a Des Moines Register/Mediacom Iowa poll published Saturday found. Another 3% told pollsters they intended to vote for someone else, 2% said they wouldn’t cast a ballot at all, and 7% said they were still making up their mind.