Picking up on Simon Lester’s reaction on Friday to President Trump’s near 180-degree rhetorical pivot on the Trans-Pacific Partnership, I agree with the implication that one would be ill advised to set his watch to the man’s words. However, there are plenty of good reasons for Trump to change his mind and seek to rejoin the TPP, so maybe—just maybe—the president is beginning to see the bigger picture.

Before the 2016 election, I wrote a piece in Forbes explaining why any president would want the tools of the TPP at his or her disposal and predicted that the next president (despite both major party candidates disavowing it) would ultimately support it:

The TPP is a blueprint for securing U.S. geoeconomic and geopolitical interests now and into the future by updating the rules and institutions of international trade that facilitated 70 years of global economic expansion, poverty reduction, and relative peace. As an agreement that includes countries on four continents, the TPP is well-suited to fill the void created by the breakdown of the multilateral negotiating “round” approach to global trade liberalization. The TPP is open the new members and the fact that it has achieved critical mass (40% of global GDP represented) means that the cost of remaining outside the deal will rise with every new accession, so most eligible countries will choose to join.

As investment has begun to shift from TPP outsiders to TPP members in anticipation of implementation, non-members have been implementing various domestic reforms to improve their prospects for eventually joining. And with China’s most important trade partners joining TPP, Beijing with have no better alternatives than to embrace the TPP, as well—and accept the new rules that will rein in some of the abusive trade practices of which China is so frequently accused.

After Trump won the election, I remained unconvinced that he’d pull out. I wrote in Foreign Affairs:

The TPP offers the last best chance to achieve a fresh round of comprehensive global trade liberalization under U.S. leadership. It reasserts the primacy of the rule of law in trade and expands its coverage to aspects of global commerce that didn’t even exist when the current rules were last updated, 22 years ago. As an agreement that includes countries on four continents and is open to new members that qualify, the TPP could evolve into a vehicle for achieving a much more broad-based round of multilateral trade liberalization.

Economies accounting for nearly 40 percent of global output and one-third of trade are among the TPP’s charter members, so the deal has achieved critical mass. That heft allows the TPP’s terms to be offered to prospective new members on a take-it-or-leave-it basis. If regional investment shifts from TPP nonmembers to TPP members, the incentive to join the agreement would only grow. Many countries, including Indonesia, South Korea, Taiwan, and Thailand, have already expressed interest in joining and have begun to undertake the domestic reforms necessary to qualify for the TPP.

With each new accession to the deal, the cost of remaining on the outside would only increase. That applies to China, too, which could watch some of its most important trade partners join TPP and, at some point, concede to having no better alternatives than to embrace the TPP, as well-and to accept the new rules that would rein in some of the abusive practices for which it is so frequently criticized.

Well, the costs of remaining outside the agreement have begun and will continue to mount and be borne by the United States unless we move quickly to change course. By bailing out of TPP, which will set sail without us as the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (TPP-11) in March, U.S. exporters will be at a disadvantage when it comes to foreign market access, U.S. consumers will be deprived of lower-priced goods, and the U.S. economy will be a less attractive destination for investment.

But just as important, being outside the TPP deprives U.S. negotiators of meaningful leverage to address, curtail, and reverse China’s objectionable practices in the realm of forced technology transfer, intellectual property theft, discrimination, and state intervention—especially those practices that might not be adequately restrained by WTO rules. Standing shoulder-to-shoulder, resolutely, with other trade partners who face similar problems in China is probably the best—maybe the only—way to get Beijing to change course short of a deleterious trade war.

Although it’s far from clear whether Trump has really changed his mind about the TPP, I think he’s probably learned over the past year that his decision to withdraw came at a pretty steep cost. He may have a case of buyer’s (returner’s) remorse. Let’s hope so. Let’s encourage him to make amends. But Trump’s off-the-cuff conditionality for reentering the deal assumes a degree of negotiating leverage the United States probably doesn’t have anymore. As humbling as this may be, joining the TPP as a non-charter member is likely to mean the United States would have to give more and get less than what Obama’s USTR was able to do.

(Link to Cato Trade’s Comprehensive Assessment of the TPP.)