Montana voters chose to protect the right to an abortion in their state constitution. The ballot initiative sought to enshrine a 1999 Montana Supreme Court ruling that said the constitutional right to privacy protects the right to a pre-viability abortion by a provider of the patient’s choice.

Sheehy cut into Tester's margins from six years ago in the counties where most of the state's people live. In Bozeman's Gallatin County, Sheehy was doing about 5 percentage points