In its analysis of the latest round in the Rand Paul-Chris Christie dust-up over the future of conservative foreign policy, the Washington Post writes: “Typically, a fight produces a winner and a loser. But that’s not the case in the spat between New Jersey Gov. Chris Christie (R) and Sen. Rand Paul (R-Ky.). In their clash over national security ideology, both men stand to gain politically in the near term.” That may be true, but it isn’t the case that there is no loser here. It can be plausibly argued that in this current bout Christie and Paul both win, but that someone else still loses: Marco Rubio.

Rubio has been noticeably quiet as the conservative movement seeks to shape its approach to the world for the next presidential election. Yet it was Rubio who was the first 2016 prospect to grapple with the challenges of maintaining American global engagement in the post-Cold War world, and certainly in the post-Iraq and Afghanistan world. Rubio entered the Senate as a Tea Party favorite who advocated a robust American foreign policy. He sensed that despite the political rhetoric about bullying Americans–especially from Europe and the Middle East–those grandstanding politicians still retained the hope that America would do the thankless jobs that have fallen on its shoulders for over half a century. And as a 2012 Miami Herald profile of Rubio revealed, the senator from Florida was right:

Rubio said that, while foreign heads of state and politicians, bash the United States publicly, their tone changes in private.

“They’re begging for U.S. influence and leadership,” he said. “They’re not threatened by us. They’re not scared of us. They’re not worried about the United States being involved because we have a track record.”

That feeling was reinforced “by driving through the streets of Tripoli and seeing pro-American graffiti on the walls. Of having people come up to me on the streets and thank the United States – thank you America for what you did – by the enthusiastic greeting we received in the hospital that we visited or people we met people in the square.”

That view of international relations, gleaned from interpersonal exchanges rather than the stock anti-Americanism found in the media, informed Rubio’s belief in American global engagement. Just before that Miami Herald profile was published, Rubio gave a major foreign policy address at the Brookings Institution in which he acknowledged both the successes of the American-led postwar world and the challenge of post-Cold War superpower status:

So this is the world America made, but what is the role for America now? Is now finally the time for us to mind our own business? Is now the time for us to allow others to lead? Is now the time for us to play the role of equal partner?

I always start by reminding people that what happens all over the world is our business. Every aspect of lives is directly impacted by global events. The security of our cities is connected to the security of small hamlets in Afghanistan, Pakistan, Yemen and Somalia. Our cost of living, the safety of our food, and the value of the things we invent, make, and sell are just a few examples of everyday aspects of our lives that are directly related to events abroad and make it impossible for us to focus only on our issues here at home.

The next question I am asked is why doesn’t someone else lead for a change? Why do we always have to be taking care of all the problems of the world? Isn’t it time for someone else to step up?

I always begin my answer to that question with a question of my own. If we start doing less, who’s going to do more? For example, would a world order where China, at least as we know it right now, was the leading power be as benignly disposed to the political and economic aspirations of other nations as we are?

This is not a detailed exposition of precisely how America should address every foreign policy challenge, but a statement of purpose. It was also interpreted by many to represent Rubio’s grand entrance onto the national stage with regard to foreign affairs. And yet the truth is that as time passes, Rubio’s voice only seems to fade. And now with the debate about the future of conservative foreign policy breaking out into the open, Rubio’s silence is deafening.

Rubio’s decision to stand aside as this debate plays out has created a vacuum. Countering Rand Paul’s still vague, but seemingly retrenchment-centric, foreign policy has been left to Chris Christie–a governor without much foreign policy experience–and Congressman Peter King. Both seem to be considering a run for the presidency, though Christie is far more likely than King to ultimately run. Rubio had been collecting the experience and authority to be the advocate of an engaged America on the 2016 debate stage. Yet that debate has started already.

The obvious explanation for Rubio’s mysterious disappearance from the foreign policy debate is that he has raised his voice on other issues and is boxed in. He led the effort in the Senate to reform the nation’s immigration system, which has caused his stock among the party’s base to plummet. He has tried to win them back by stepping into the national abortion fight, offering to sponsor a bill that would restrict abortion in a way that is popular nationally but especially among the conservative grassroots.

And the assumption is that taking on Rand Paul over domestic surveillance would once again put him at odds with the base. It’s actually unclear whether retrenchment chic is truly sweeping the conservative movement for three reasons. First, Paul is the only high-profile politician occupying that space right now; as I wrote late last week, other libertarians like Justin Amash actually favor foreign intervention and sanctions. Second, we don’t actually know if Paul himself feels this way, because he has been unclear on certain aspects of the issue–evidence, perhaps, that he isn’t sure the base actually believes in retrenchment either. And third, Rubio’s silence has contributed to this confusion because there is no erudite counterweight to Paul, certainly not one with grassroots and Tea Party bona fides.

There is good reason, in other words, this debate was always expected to be between Paul and Rubio. Paul showed up. Whether or not he has an apparently justifiable reason for it, Rubio has not.