It’s clear now that Team Hillary is worried about Sen. Bernie Sanders.

How else do you explain Hillary Clinton’s reversal on the Trans-Pacific Partnership pact? As secretary of state, Ms. Clinton repeatedly championed the deal, even as negotiations continued. There was no hint of reservation back then. By CNN’s count, she spoke publicly in favor of the deal 45 times.

"This TPP sets the gold standard in trade agreements to open free, transparent, fair trade, the kind of environment that has the rule of law and a level playing field," then Secretary Clinton said in a November 2012 visit to Australia.

But on Wednesday, with the 12-nation deal finalized, Ms. Clinton said in interview she has had a change of heart.

"I have said from the very beginning that we had to have a trade agreement that would create good American jobs, raise wages and advance our national security and I still believe that is the high bar we have to meet," Clinton said. "I don't believe it's going to meet the high bar I have set."

This sure looks like a political calculation. Vermont Sen. Bernie Sanders, with strong showings in the New Hampshire and Iowa polls, has emerged as a genuine threat in Ms. Clinton’s quest for the Democratic presidential nomination. Sen. Sanders’ populist message is resonating. It has always included opposition to trade deals such as the TPP.

This newspaper supports agreements, like the TPP, that set up rules for fair and vigorous international trade. The ability to tap into the vast Asia-Pacific market will, on balance, mean more and better paying American jobs.

But we also admire the courage of conviction. While we disagree with Sen. Sanders on TPP, he has been consistent in his concern that these deals also displace jobs.

As for courage of conviction, the same cannot be said of Ms. Clinton.