Filibuster at serious risk as Sinema begins her Senate exit

Politico.com - For more and to sign up click here Sen. Kyrsten Sinema’s decision to retire at the end of the year makes at least one thing very clear: The filibuster is in big trouble. Two of its staunchest defenders in the Democratic Caucus, Sinema and Sen. Joe Manchin (D-W.Va.), are now leaving. And Senate Minority Leader Mitch McConnell stepping down as GOP leader won't do anything to shore up the Senate’s…