The February 11 Democratic debate was critical for both former Secretary of State Hillary Clinton and Senator Bernie Sanders. Clinton, reeling from a 22-point defeat in the New Hampshire primary, looked to expose some of Sanders’s weaknesses as a candidate—including his lack of foreign policy experience.

Indeed, this is where he is most vulnerable. As Washington Post columnist David Ignatius recently stated, “Foreign policy is the hole in Sanders’s political doughnut.”

So far, foreign policy discussions between the two Democratic candidates have featured the same back-and-forth: Clinton emphasizes her knowledge and experience by referencing her time spent as Secretary of State, while Sanders argues that judgment trumps experience—and his judgment is superior to Clinton’s because of his 2002 vote against the U.S. invasion of Iraq.

Just like Sanders, this particular talking point is getting old.

Though emphasizing his opposition to the Iraq War may resonate with voters—a 2015 Quinnipiac University poll found that 59 percent of registered voters thought the invasion was the “wrong thing” for the United States to do—it is only a matter of time before Sanders is mocked for defaulting to talking about his judgment when asked about specific foreign policy issues. Clinton whacked him on this during the debate, saying, “I do not believe a vote in 2002 is a plan to defeat ISIS in 2016.”

Sanders needs some new material.

Richard Haass, president of the Council on Foreign Relations, might be able to help. His recently published book, Foreign Policy Begins at Home: The Case for Putting America’s House in Order, argues that the greatest threats to U.S. national security are crumbling infrastructure, an outdated immigration system, second-class schools, and growing debt.

“Shortcomings here at home directly threaten America’s ability to project power and exert influence overseas, to compete in the global marketplace, [and] to generate the resources needed to promote the full range of U.S. interests abroad,” Haass warns.

This is a talking point tailor-made for Sanders. The senator is much more focused on domestic policy than foreign affairs; his main talking points—establishing universal health care, fixing a “rigged economy,” and advancing campaign finance reform—are all domestic in nature.

But as Haass rightly emphasizes in his book, there is a strong connection between U.S. domestic strength and ability to defend our borders and project power worldwide.

Outdated infrastructure in many areas of the United States creates a less appealing environment for businesses than many other developed nations around the world, acting as a disincentive to companies looking to operate on U.S. soil. Second-rate schools place the United States at a disadvantage as other developed countries like South Korea, Japan, and the United Kingdom consistently score higher on global measures of educational achievement (though the methodology behind these rankings is far from perfect).

Lastly, as Sanders never fails to point out, “We have today a campaign finance system which is corrupt, which is undermining American democracy.”

In future debates, Senator Sanders should call attention to the fact that his domestic agenda will put the United States in a better position to defend itself and its interests abroad. This is an accurate statement that reflects what the public knows of his views on foreign policy as well as his clear emphasis on domestic issues. On foreign policy issues, Sanders has repeatedly voiced opposition to U.S.-led regime change and pushed for regional allies to assume more responsibility for regional conflicts.

“In future debates, Senator Sanders should call attention to the fact that his domestic agenda will put the United States in a better position to defend itself and its interests abroad.”

Pundit Stephen Pampinella wrote an exceptional piece in Foreign Affairs laying out a foreign policy agenda for Sanders that “build[s] upon U.S. President Barack Obama’s liberal internationalism while rejecting Clinton’s embrace of American exceptionalism.”

Pampinella’s foreign policy vision for Sanders, which he dubs “Bernie’s World,” is also consistent with what Sanders has made clear thus far of his views—and his choice of Franklin Delano Roosevelt as his favorite U.S. president. Given Sanders is such a domestically focused candidate, however, it might make sense for his foreign policy message to be encapsulated within his agenda for radical domestic reform.

Either way, Sanders’s talking point on judgment and Clinton’s 2002 Iraq War vote is getting stale, and pundits and journalists alike have begun to criticize his lack of clear foreign policy positions.

Sanders will need to develop more concrete answers to specific foreign policy issues, such as the future of U.S. involvement in Afghanistan or a strategy to counter aggressive Chinese behavior in the South China Sea. But pointing out that foreign policy begins at home is a powerful and accurate argument that may help Sanders drive home his domestic agenda.

He is going to need to hire some foreign policy staffers soon, though.

Image: Bernie Sanders appears at the ABC Democratic Debate on December 19, 2015.

(Ida Mae Astute/ABC, Creative Commons)

Brian Garrett-Glaser is a freelance writer and geopolitical analyst with experience working in D.C. think tanks, government contracting, and the wonderful world of lobbying. He holds a degree in international conflict analysis and resolution from George Mason University, and his writings have been published by the Council on Foreign Relations and the American enterprise Institute. He currently works for a government contracting company as a Public Affairs Specialist. Follow him on Twitter.