President Trump “is aggressively campaigning for Republican Senate candidates around the country and belittling their Democratic rivals, with one notable exception — North Dakota Sen. Heidi Heitkamp (D-ND),” the Washington Post reports. “Trump’s affinity for Heitkamp, who got a shout-out and a handshake at a recent White House bill signing, has frustrated top Republicans who see winning her Democratic seat as crucial to holding onto their fragile 51-to-49 majority.