By Mohamed A. El-Erian

Much will be written and said about the defeat that the U.K.'s prime minister, David Cameron, is likely to experience by opposing the appointment of Jean-Claude Juncker as the next president of the European Commission.

In judging whether Cameron took a valiant, principled stance or made a big strategic blunder, history will need to look beyond what happens next in the European Union or even whether Britain remains an EU member down the road. History also will have to judge whether Cameron applied his principles to other institutions in desperate need of similar reforms.

Cameron appears to have been driven by two factors in his determined attempts to block Juncker’s appointment. First, he believes that the selection process itself is antiquated, frustrating Europe’s pivot to a better-managed, inspiring and visionary future. As such, the credibility of Europe’s historic (and challenged) regional integration process could be damaged. Second, he believes that Juncker is not the right person for the task at hand.

While other EU members seem to sympathize with Cameron’s view, few, if any, wish to disrupt their established institutional approach — and for good reason. It would involve a whole set of implicit contracts that would need to be painfully renegotiated, with uncertain outcomes for each country involved.

Reading the writing on the wall, most politicians would have abandoned the fight for a better and modernized appointment process. Not David Cameron. He has courageously campaigned for change even as his allies drop out, one after the other, from this institutional fight.

While it is hard to know for sure, I suspect that two major considerations have entered Cameron’s calculus: first, the desire to use this post-crisis juncture in the EU to undertake governance reforms that many feel necessary but few have the stamina to pursue, and second, the belief that, whatever the outcome, his stance will play well to a domestic British audience that is historically deeply suspicious of Brussels.

Cameron’s calculus is far from risk-free. His defeat could be humiliating on the European stage. Britain may subsequently suffer when it comes to other high-level appointments in Brussels, including when it involves trying to place like-minded officials from other member countries in office. Cameron may also have inadvertently fueled more anti-EU sentiment in Britain ahead of the national referendum he has promised will take place after the next parliamentary elections.

If Cameron is truly driven by principles, he needs to bring Britain’s stance to bear on another outmoded and feudalistic appointment process — that for the International Monetary Fund and the World Bank. And the sooner he does that, the greater the prospects for reforming a practice that undermines the credibility and legitimacy of these important multilateral institutions.

Nationality still plays a critical role in who heads the IMF and World Bank, 70 years after their creation. Leadership of the IMF is reserved for a European and leadership of the World Bank for an American.

While there has been some talk of making the selection process more open, the effort hasn't satisfied the institutions' constituencies and lacks credibility because so little progress has been made in moving toward a comprehensive and transparent, merit-based process. And with recent appointments at both entities having to be done rather quickly due to the sudden resignations of incumbent leaders, little time has been dedicated to shaping a more modern selection process.

Now is a great time for Cameron to pursue long-delayed reforms to these selection processes. Both institutions are under the leadership of respected, first-term heads who would face little opposition to having their terms extended. And both have been spearheading reforms, be it Christine Lagarde’s approach to selecting a new deputy managing director at the IMF or Jim Kim’s institutional changes at the World Bank.

As such, reforms could be pursued thoughtfully and deliberately, rather than be rushed — as would be the case if the IMF and World Bank waited to act until the eve of the next appointments. Under Cameron's leadership, taking a reform stance would also prove that Britain is indeed dedicated to modernizing regional and multilateral governance, regardless of any short-term friction.