With prospects for a Senate border compromise looking increasingly murky amid opposition from former President Donald Trump, further substantial U.S. military assistance to Ukraine and Israel appears increasingly in doubt. Some congressional Republicans had earlier insisted that the assistance move forward only together with border security measures. Working to block compromise is likely to prove damaging not only to U.S. interests but also to the political interests of the former president and his congressional allies.

While all three issues are important, the border as well as U.S. assistance to Ukraine and Israel—the connection among them is inherently a political one. Their bundling together is an effort to create a no-lose situation for former President Trump and his backers, especially in the House of Representatives. 

Had President Biden rejected the compromise, he would have assumed political responsibility for outcomes along the border, in Ukraine, and in Israel’s war on Hamas. Conversely, if Mr. Biden and congressional Democrats accepted the compromise, congressional Republicans would achieve a demonstrable policy victory over the Democrats—on the border—by standing tough during a bitter campaign season. The latter pathway appears to be collapsing under fire from Mr. Trump, who reportedly fears that it might give Mr. Biden a victory in the run-up to the presidential election.

This is an understandable calculation for a political candidate seeking the White House and prepared to accept the costs to U.S. interests from continued turmoil along the U.S.-Mexico border, a dramatic weakening of Ukraine’s ability to resist Russia’s invasion, and falling short in supporting Israel. But is it an accurate one?

One problem for Mr. Trump and his congressional supporters is that in visibly blocking a bipartisan compromise that other Republicans could be prepared to accept, they will own a very large share of the responsibility for conditions along the border, in Ukraine and in Israel between now and Election Day, November 4. The next nine months could see important shifts in all three areas. 

Indeed, if security conditions along the border continue to deteriorate, President Biden and congressional Democrats can blame the GOP for blocking funding to improve them. If Ukraine’s forces lose significant ground—or suffer a catastrophic defeat, as some fear—Mr. Trump and his allies will own it. The former president’s record in supporting Israel would likewise take a significant hit.  Mr. Biden and his backers would embrace these or similar talking points, as would many outside observers in the media and elsewhere.

Circumstances in Ukraine might be the most unpredictable and, therefore, the most dangerous politically for the former president and his congressional supporters. One could reasonably expect that the situation along the U.S.-Mexico border will not change materially before November—or that extensive televised jousting and hand-waving will leave voters sufficiently confused to avoid significant political fallout. One might also argue that Israel faces growing pressure to wind down its military operations, including from the Biden administration and that blocking or delaying U.S. military assistance would not excessively impede Israel. Or that Americans are so divided over Israel’s tactics that any votes to be gained in backing Israel would be lost elsewhere. To the extent that combining measures to support Israel with assistance to Ukraine was itself a political calculation, some might even hope that U.S. military aid to Israel could eventually proceed on a separate track—though this seems more challenging as the war in Gaza progresses and criticism of Israel’s approach to it mounts.

Withholding further significant military assistance to Ukraine could be far more consequential not only on the ground but also in voting booths.

Here, it might be helpful to recall America’s unfortunate experience with Vietnam. After signing the Paris Peace Accords and withdrawing U.S. troops in 1973, the United States continued to provide financial support to South Vietnam. During the next two years, the Ninety-Third Congress—under Democratic Party control in both houses—reduced and blocked U.S. aid. By 1975, South Vietnam’s forces collapsed, and the U.S. military evacuated American diplomats and others from a U.S. embassy rooftop. The iconic photos have come to symbolize how former President Richard Nixon’s effort at “Peace with Honor” became what many later saw as a humiliating defeat.

What Mr. Trump and congressional Republicans might also consider is how the 1960s and 1970s-era Democratic Party divisions over Vietnam, culminating in curtailing U.S. support, contributed to significantly greater public confidence in Republicans’ handling of U.S. national security policy for almost all of the subsequent period. Highly respected Democratic-leaning foreign policy experts themselves argued this case in explaining (in part) why 2004 Democratic candidate John Kerry failed to defeat then-President George W. Bush despite the latter’s unpopularity. Some dispute whether the reduction of U.S. support was the principal reason for South Vietnam’s loss; from a political perspective, what actually occurred is far less important than the narratives that came to dominate American electoral politics.

Mr. Trump’s alternative—supporting a compromise—seems more likely to yield electoral advantage both immediately and in the long term. First, it would establish Mr. Trump as not only a political power broker but as a policy broker, which largely eluded him on Capitol Hill during his previous term. Only with his help could President Biden move a compromise bill through Congress. Second, it would help to define the former President as a “builder” rather than a “breaker” in American politics, something that many independent voters have not yet seen and yearn for. Third, the move would be so surprising to many that it would dominate media discussion for some time. Mr. Trump’s role as Ukraine’s savior would be the center of discussion on air, online, and in print. Fourth: if elected, Mr. Trump would hold much greater leverage if he pursued a negotiated settlement with Russia, as he has suggested he would.

Changing course in this manner would require very little from Mr. Trump, who is quite flexible politically and could likely find a way to demonstrate that he forced changes in a compromise package to provide public justification for his revised position. That explanation would be far easier to offer than the one many will seek in September or October if Russia should prevail in Ukraine. Then, the question could be, “Who lost Kyiv?”

Paul J. Saunders is President of the Center for the National Interest and a Senior Advisor to the Energy Innovation and Reform Project. He was a State Department Senior Advisor from 2003 to 2005.

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