CUMBERLAND, Maine — Sara Gideon, her voice hoarse on a cold Friday night, stood in the center of a fairgrounds stage as the headline act at a drive-through rally, making a closing pitch to a chorus of appreciative car honks and headlight flashes for a government dominated by Democrats that would move aggressively to address climate change, economic and racial inequality and out-of-control health care costs.
A day earlier, Senator Susan Collins, Republican of Maine, had barreled across the state in her signature campaign bus with a very different message, highlighting the billions of…
