Democratic presidential candidate Hillary Rodham Clinton speaks Oct. 7 at the Westfair Amphitheater in Council Bluffs, Iowa. (Nati Harnik/Associated Press)

BOWING TO pressure from the Democratic Party’s ascendant protectionist wing, would-be presidential nominee Hillary Clinton has come out against President Obama’s freshly negotiated Trans-Pacific Partnership (TPP) trade agreement. The most hopeful thing to be said about this deeply disappointing abandonment of the president she served, and the internationalist tendency in Democratic ideology she once embodied, is that it is so transparently political.

There is no way that Ms. Clinton can oppose the 12-nation deal on its merits. In part, that’s because she doesn’t know all the details, as she acknowledged. More to the point, the reasons she offered for her view could not have been convincing, even to her. There was nothing in the deal about alleged currency manipulation by U.S. trading partners, she complained. Yet the biggest manipulator, China, isn’t a party to the pact. As the Obama administration argued, trade pacts by definition deal with tariffs and the like, not monetary policy; currency rules might have been construed to limit the Federal Reserve’s options unduly. Ms. Clinton also told Judy Woodruff of PBS that “pharmaceutical companies may have gotten more benefits and patients and consumers fewer.” This, about an agreement in which U.S. negotiators made such significant concessions on U.S. drugmakers’ intellectual property rights that the deal may lose votes among drug industry allies in Congress.

And of course, Ms. Clinton’s opposition to the TPP flies in the face of her repeated statements to the opposite effect when she was Mr. Obama’s secretary of state — and after. “It’s safe to say that the TPP won’t be perfect — no deal negotiated among a dozen countries ever will be — but its higher standards, if implemented and enforced, should benefit American businesses and workers,” Ms. Clinton wrote in her post-State Department memoir, “Hard Choices.” As Ms. Clinton understood then, the TPP was not only about economics but also about geopolitics. It’s particularly crucial to Mr. Obama’s essential effort to strengthen U.S. ties to Japan and other East Asian nations, thus counterbalancing China, a “rebalance” for which Ms. Clinton once proudly claimed some authorship.

Not content to cast doubt on her seriousness as a steward of U.S. foreign-policy interests, especially the alliance with Japan, Ms. Clinton compounded the error by going out of her way to trash Mr. Obama’s trade deal with South Korea, volunteering to Ms. Woodruff that that agreement, in effect for barely 3½ years, “doesn’t have the results we thought it would have in terms of access to the markets, more exports, etc.” Though both U.S. allies, Japan and South Korea are rivals with each other. It therefore takes some doing to offend them both, but Ms. Clinton’s waffling on trade may have done the trick.

To be sure, Ms. Clinton salted her anti-TPP statement with qualifiers: “What I know about it.” “As of today.” “I am not in favor of what I have learned about it.” And so on. In other words, there is still a chance that later on, if or when she’s president, and it is to her advantage, she may discover some decisive good point in the TPP that would let her take a different position without, technically, contradicting herself. Cynical? Perhaps, but as we said, that’s the hope.