SEIU retweeted this New York Times article:

In fact, the greatest impediment to unions is weak and anachronistic labor laws.  It’s time to add the right to organize a labor union, without employer discrimination, to Title VII of the Civil Rights Act, because that right is as fundamental as freedom from discrimination in employment and education. This would enshrine what the Rev. Dr. Martin Luther King Jr. observed in 1961 at an A.F.L.-C.I.O. convention: “The two most dynamic and cohesive liberal forces in the country are the labor movement and the Negro freedom movement.  Together, we can be architects of democracy.