Now, let’s extend the spirit of bipartisanship to another area where it has been sorely lacking: national security policy. Where for many decades after World War II our country heeded Sen. Arthur Vandenberg’s admonition that “we must stop partisan politics at the water’s edge,” today naked partisanship impinges on virtually every aspect of foreign and security policy, making them dangerously dysfunctional.

This shows up most clearly in the huge trust gap between the White House and the Congress. Increasingly, presidents conduct their foreign policy without seeking Congressional backing, and often in the face of Congressional hostility. Rather than an ally or partner, Congress is seen as simply an obstacle to be avoided.

To change this dynamic, we must recognize that unity in foreign affairs matters. The appearance—and the fact—of political disunity on foreign policy weakens public confidence in our elected leadership, confuses our allies and emboldens our enemies.

What is the world to think, for instance, when 47 Republican senators sign a letter to Iran’s leaders in a clumsy attempt to undercut the president’s authority to negotiate a nuclear deal?

Such partisanship and disunity make it virtually impossible to construct a comprehensive national security strategy, leading presidents to conduct foreign policy on an ad hoc basis.

The partisan gulf between the president and Congress was illustrated most clearly by the debate and votes on the Iran nuclear agreement, where not a single GOP legislator voted in favor. Opposing a president on a foreign policy matter is not, in itself, a partisan act.  Many members had thoughtful reasons for doing so.  But the cavernous distance between the President and the Republican Congress was stunning, especially given the gravity of the issue and the fact that the partisan argument was over methods, not goals.

Unfortunately, the divide over the Iran deal is not the exception, but part of a disturbing trend. Consider:

--Treaties have lost virtually all their usefulness as a foreign policy tool because Congress won’t pass them—or even debate them.  The last time Congress approved a major treaty was in 2010, the New Start Treaty for modest nuclear weapons reductions with Russia. Since then, most pending treaties haven’t even had hearings because they are considered political non-starters.

--The Obama administration in 2012 unilaterally discarded a two-decade old cooperative practice of seeking Congressional pre-approval for arms sales to foreign governments.  This process greatly facilitated consultation between the branches and ensured that our government was usually unified on the sensitive issue of whether to sell or withhold American-made weapons.

--Congress has become paralyzed in the face of foreign policy crises. The 2011 intervention in Libya and the ongoing operations in Syria proceeded without proper Congressional debate or authorization. Both ends of Pennsylvania Avenue share the blame: the Obama administration never made Congressional consultations an integral part of its policy, and lawmakers shied from complex debates that might have required difficult votes.

Rapidly changing developments around the globe—ranging from new cyber threats to Russian and Chinese assertiveness to the refugee crisis--call for a new consensus on foreign policy among the two parties and the two branches, similar to what occurred after World War II and the end of the Cold War. But we don’t have one, and no one is even attempting to forge one.

With President Obama seeking to secure his legacy as his final term winds down, and with the temporary banking of the partisan fires on Capitol Hill, now is the time to start laying the groundwork so the next president and Congress can work together.

At The Lugar Center, we publish a Bipartisan Index that we hope will encourage lawmakers to find common ground across the aisle.  We co-host bipartisan forums on arms control and global food security for Congressional staff, as well as workshops on bipartisan Congressional oversight of the executive branch.

But it will take more than goodwill or good intentions to achieve a more unified foreign policy framework. It will take commitment, effort and, above all, persistence by the next commander-in-chief, who must make it a priority to build a national security consensus, not as a means to an end, but as an end in itself.

This op-ed originally appeared in The Hill.