Sam Forstag, a former firefighter, has declared victory in a competitive Democratic House primary in western Montana, but The Associated Press has not called the race. “We did it, Montana,” Forstag, who was joined on the campaign trail in recent days by Representative Alexandria Ocasio-Cortez, wrote on social media. He faced Ryan Busse, a former Democratic nominee for Montana governor, in a primary in a conservative-leaning district that Democrats hope to flip.