Rep. Ben Cardin on Thursday accused China of “continued denial of basic international labor standards” and, along with a prominent conservative Republican, Rep. Chris Smith of New Jersey, asked the U.S. trade representative to investigate its practices.

Cardin, D-3rd, is a longtime advocate for human-rights issues, particularly in China, but his action drew a quick attack from the Maryland Republican Party, which said the congressman “says one thing, does another” because in 2000 he voted to approve permanent normal trade relations with China.