Sen. Joe Manchin (D) wants all sitting senators to sign a pledge saying that they won’t campaign against each other. This is in the wake of Vice President Mike Pence sending several tweets explicitly aimed at Manchin and his vote against the Republican tax bill.
Manchin: "If you go to work and you know somebody's been in your state campaigning against you -- it might be a person you've worked with and you considered a friend -- I can tell you, that deteriorates that trust and that friendship level that you had before."
The pledge would only be for races with sitting senators and also applies to fundraising, social media, direct mail, and attack ads. (CNN)