In Annapolis on Friday, Jamie Raskin was a rockstar. If he only got a raucous, welcoming round of cheers when he walked into a Democratic breakfast club meeting, it was because the appreciative audience was mostly silver and may have preferred not to stress their aging knees. But the spirit was there. “Our last great Republican president, Abraham Lincoln, didn’t know whether Americans could long survive half slave and half free,” said the congressman from Montgomery County, former state senator, constitutional scholar, ranking verbal pugilist on the powerful, fractious House Oversight Committee and unexpected TikTok sensation.