By Manu Raju, Alison Main, CNN (CNN) — Sherrod Brown stood in front of dozens of supporters at a suburban watering hole, talking glowingly about his final day in the US Senate in 2024. Then he caught himself. “Well, I thought it was my last night,” said Brown, eliciting applause in the room. “There are going to be more nights now.” The former three-term senator from Ohio is mounting a comeback bid that’s critical to national Democrats’ hopes of …