Sen. Martin Heinrich of New Mexico endorsed Graham Platner on Tuesday in Maine's Democratic Senate primary -- the latest sign of a growing push inside the party against Senate Minority Leader Chuck Schumer's preferred candidate, Gov. Janet Mills.

The top Democrat on the House Appropriations Committee is pinning the blame on Republicans for flight delays, hourslong jams at Transportation Security Administration checkpoints and the overall chaos at major airports across the U.S. -- while her party blocks Department of Homeland Security funding.