The 2024 contest is shaping up to be one of those, especially on the Republican side, where the election could solidify the party’s move away from the assertive internationalism of the Ronald Reagan era and toward the more isolationist views associated with former President Trump.

Such a move won’t come without a struggle, though: Reagan-era policies still draw strong support from many of the party’s most powerful senators and their allies in the party’s foreign policy establishment.

An early round of that fight burst into public view this week after Florida Gov. Ron DeSantis released a statement in which he downplayed the importance of the war in Ukraine and appeared to side with Trump in opposing strong U.S. support for Kyiv.

But the debate within the GOP goes well beyond DeSantis and his effort to gain support among conservative primary voters who currently back Trump.

Nor are the Democrats immune. In both parties, changes are coming on major foreign policy issues, driven in part by big differences between the views of the millennial generation and older groups. The unfolding presidential campaign will test how far public sentiment has shifted.

Republicans ditch Reaganism

DeSantis’ statement on Ukraine was notable both as the first major foreign policy position of his nascent presidential campaign and because he wrote it in response to a query from Fox News commentator Tucker Carlson, the right’s leading opponent of U.S. support for Ukraine.

“Becoming further entangled in a territorial dispute between Ukraine and Russia is not” one of America’s “vital national interests,” DeSantis said.

Republican figures associated with the party’s internationalist wing, including Sens. Lindsey Graham of South Carolina, John Cornyn of Texas and DeSantis’ home-state Sen. Marco Rubio, quickly criticized the Florida governor. Graham accused DeSantis of trying to appease Russian President Vladimir Putin, likening him to Neville Chamberlain, the British prime minister of the 1930s who sought to placate the Nazis by forcing neighboring Czechoslovakia to give up territory.

Two Republican presidential hopefuls, former South Carolina Gov. Nikki Haley and former Vice President Mike Pence, also criticized DeSantis (and Trump, by implication) on Ukraine, setting up the war as one of the early dividing lines in the GOP field.

“The Russian government is a powerful dictatorship that makes no secret of its hatred of America,” Haley said in a statement, adding that Putin is “attempting to brutally expand by force into a neighboring pro-American country” and that the U.S. has a strong national interest in Ukraine’s success.

The dueling statements illustrate how the divide within Republican ranks over Ukraine has widened.

When Russia invaded Ukraine a year ago, Americans in both parties condemned the action and backed strong support for Kyiv’s defense. Immediately after the invasion, about 8 in 10 people in both parties supported sending additional arms and military supplies to the Ukrainians, according to a March 2022 poll by the Chicago Council on Global Affairs.

Over time, that picture changed. When the Chicago group repeated its poll in November, Democratic support for military aid remained at nearly the same level, but Republican support had dropped 25 points, to just a bare majority.

More recent polls have shown continued erosion. A January survey by the Pew Research Institute found that 40% of Republicans and independents who lean to the GOP thought the U.S. was providing “too much support” for Ukraine; 17% said the U.S. was not doing enough and 24% said the amount was about right.

Among Democrats, by contrast, just 15% said the U.S. was providing too much help.

Trump has driven some of the growing partisan divide: He’s continually opposed President Biden’s pro-Ukraine policy and has called for negotiations that could lead to Ukraine giving up some of its territory in exchange for peace.

Some of Trump’s supporters and family members have gone further: At the Conservative Political Action Conference this month, Rep. Marjorie Taylor Greene (R-Ga.), attacked Ukrainian President Volodymyr Zelensky, saying that he “wants our sons and daughters to go die in Ukraine.” Kari Lake, the former candidate for Arizona governor, declared that “we have hundreds of billions of dollars of our hard-earned American money being sent overseas to start World War III.”

GOP voters don’t, by and large, share Trump’s sympathy with Putin, said Carroll Doherty, director of political research at Pew.

“Russia is still viewed negatively” by a large majority of Americans across party lines, he noted. But Americans’ concern about “the threat from this situation has gone way down,” and that has opened the way for Republicans to question the amount of aid the administration is sending Kyiv.

Republicans who identify as “very conservative” — a group highly critical of Biden — are especially likely to say the U.S. is doing too much for the Ukrainians, Doherty noted.

But the division within the GOP on foreign policy goes beyond Trump and Ukraine, and on several issues, the divide comes along lines of age.

“There is a generational shift underway in the Republican Party on its approach to foreign policy issues,” said Republican pollster Kristen Soltis Anderson, citing polling by her firm, Echelon Insights. The generation gap on foreign policy “has been around a bit longer” on the Democratic side, “but now we’re seeing it spread” to the GOP, she noted.

Republicans have long supported big defense budgets, for example — “peace through strength,” as Reagan put it. In a recent Echelon poll, Republicans older than 50 overwhelmingly stuck with that view, saying it would be “a bad thing” for the U.S. if Congress were to cut the federal budget “primarily by cutting back on defense spending.”

But Republicans younger than 50 were almost evenly divided on whether such a cut would be good or bad for the country. They were more open to cutting defense than were older Democrats, the poll showed. Younger Democrats were the most likely to back a defense cut.

That split is already playing out in the House, where some GOP lawmakers have talked of cutting the Pentagon budget, complicating efforts by Speaker Kevin McCarthy (R-Bakersfield) to come up with a unified party position.

An even more striking split showed up when Echelon asked whether it would be in U.S. interests to defend Taiwan against a Chinese invasion — something Republican officials have backed since the Chinese Communist Party took power in Beijing in 1949.

Younger Republicans were divided evenly on whether supporting Taiwan would be in U.S. interests, putting them at odds with older Republicans and both older and younger Democrats, among whom support for Taiwan outpaced opposition by better than 2 to 1.

Democrats have their own generational divide on some foreign policy issues, most notably the Middle East.

Data released Thursday by Gallup showed that for the first time in Gallup’s polling, going back to 2000, Democrats said they sympathized with Palestinians more than with Israelis in the long-standing conflict between the two: 49% of Democrats said they sympathized more with Palestinians, 38% with Israelis and 13% said they favored neither side.

Overall, a majority of Americans, 54%-31%, sympathize more with the Israelis, the poll found, but the gap between the two in U.S. opinion has narrowed significantly.

The latest figures come after a decadelong slide in the share of Democrats who have more sympathy for Israel — a trend that started when Israel’s then-prime minister, Benjamin Netanyahu, openly criticized President Obama, sped up as Netanyahu forged an alliance with Trump and accelerated further with Netanyahu’s return to power after a brief period in opposition. He currently heads a right-wing government that has alienated many American liberals, including many American Jews.

Much of the shift in U.S. opinion has come from millennials, whose sympathy for the Israelis has dropped sharply over the last decade, the Gallup numbers show.

The effect on U.S. policy may be muted for now because an older, more pro-Israel generation of Democrats continues to hold sway, most notably Biden. But over time, the skepticism many younger Americans have about the use of U.S. power overseas inevitably will change American policy.

Millennials and younger Americans have grown up mostly seeing examples of American failures or stalemates, Anderson noted. “It’s harder for us to point to examples of where America being a strong force in the world has yielded benefits.”

Those younger voters probably will make up the majority of U.S. voters by 2028, if not sooner.

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