Bernie just picked up his first endorsement from a fellow senator: https://t.co/Ndnw4RYhbA pic.twitter.com/MG4raWVrqw

— Slate (@Slate) April 13, 2016

Sen. Jeff Merkley (D-Oregon) has become the first senator to endorse Bernie Sanders for president, in a lengthy, impassioned op ed published in The New York Times.