“I think he’s angry but he keeps it under control. I think he knows the consequences of lashing out at Manchin and Sinema are just going to be counterproductive,” said Ross K. Baker, a professor of political science at Rutgers University who has served several stints as a Senate fellow. “What you do in his situation, given his personality, is you express mild irritation in an oblique way. You get it on the record,” he said of Biden. “It’s interesting because it’s done as a kind of an observation rather than an accusation.”... “At what point is Biden is going to get in here, get his hands dirty, roll up his sleaves and say, ‘Enough is enough. I got elected with a mandate. Whether you’re running for reelection or not, it doesn’t matter, this is my agenda. You’re a member of this party, you better play or we’re not going to pass anything’?” said one Senate Democratic aide.