Sen. Bernie Sanders introduced legislation on Wednesday calling for a $15 federal minimum wage, taking another step to differentiate himself from Democratic presidential frontrunner Hillary Clinton, who has yet to echo that call.

And in doing so, Sanders has also put many of Clinton’s congressional supporters in a tough spot. A companion bill in the House, introduced by Rep. Keith Ellison (D-Minn.), already has 25 cosponsors. Thirteen of those lawmakers have endorsed Clinton for 2016.

“All of our workers, from coast to coast, need at least 15 bucks an hour,” Sanders said Wednesday at a rally on Capitol Hill, where federal contract employees who work in the Capitol were striking to protest their wages. He said the current federal minimum wage of $7.25 an hour “is a starvation wage – it’s got to be raised to a living wage.”

For Clinton, voicing support for an unquantified “living wage” seems to be as far as she will go. She has given some support to the push for $15 an hour: Last month she spoke, via telephone, at the “Fight for 15” conference sponsored by the Service Employees International Union, a group with 1.9 million that has been leading the charge for the $15 minimum wage. But she hasn’t committed to a specific dollar amount.

“I support the local efforts that are going on that are making it possible for people working in certain localities to actually earn 15” dollars an hour, Clinton said in New Hampshire on July 16.

Lessening economic inequality has emerged as a major theme of Clinton’s campaign, with proposals aimed at corporate profit-sharing, a more progressive capital gains tax and infrastructure spending. But on the wage front, Clinton has instead emphasized the need for states and municipalities to follow New York, Los Angeles and St. Louis by raising wages to $15 an hour.