Senator Sanders has in no way said that Secretary Clinton’s experience and service are insufficient.
What he argues is that Senator Clinton has disqualified herself to represent the interests of everyday Americans from the highest office in the land through her choices and actions.
Sanders’ Press Release
“I don’t believe that she is qualified if she is through her super PAC taking tens of millions of dollars in special-interest funds.
“I don’t think that you are qualified if you get $15 million from Wall Street through your super PAC.
“I don’t think you are qualified if you voted for the disastrous war in Iraq.
“I don’t think you’re qualified if you supported almost every disastrous trade agreement.
“I don’t think you are qualified if you supported the Panama free trade agreement, something I very strongly opposed, which has gave the green light to wealthy people and corporations all over the world to avoid paying taxes owed to their countries.”
Highlighting is mine.
YMMV