The message behind Bob Corker's public Trump intervention

Sen. Bob Corker at a Senate Budget Committee meeting. Photo: J. Scott Applewhite / AP

That escalated quickly. After a nasty Twitter back-and-forth with President Trump on Sunday morning, retiring Senate Foreign Relations Chair Bob Corker (R-Tenn.), told the N.Y. Times' Jonathan Martin that Trump's "reality show" could set the nation "on the path to World War III."

Why it matters: A Republican close to the White House told me: "These comments now shape the criticism of the President going forward. Corker's comments will be the catalyst for all the doubts about Trump's fitness ... [H]e has sewn the strands of doubt about Trump into a vivid tapestry."