Elizabeth Warren’s Democratic rivals are putting pressure on her campaign to explain the extent of her support for “Medicare for All” and to detail whether she would accept any alternatives as president.

Warren, a Massachusetts senator, declared on the debate stage in June that she was “with Bernie on Medicare for All,” referring to Bernie Sanders, the the longtime champion of “Medicare for All,” which would enroll everyone living in the U.S. into a government plan and abolish nearly all private health insurance.