But just because Clinton doesn't say Sanders's name doesn't mean he isn't on her mind -- a lot. He quite clearly is, with the latest piece of evidence being her decision, announced Wednesday afternoon, to oppose the Trans-Pacific Partnership. TPP is a massive trade deal that the Obama administration views as one of its second-term legacy items and that Clinton, as secretary of state, was on the record as supporting.

It's not hard to see that Clinton, concerned with the surprisingly strong challenge by Sanders from her ideological left, is working to put out that fire by allowing zero distance between her and the Vermonter on these two high-profile issues.

And yet, Clinton decided to reverse herself on TPP -- no matter what her campaign says, she was a supporter of the deal -- and take the flip-flopper flak rather than risk putting distance between herself and the party base.

Clinton also may still be stung by the slings and arrows she took from Barack Obama during the 2008 primary campaign for her support of the North American Free Trade Agreement (NAFTA) during her husband's presidency.