The Republican debate has an unplanned theme: This isn't Ronald Reagan's party anymore

This surely wasn't the plan, but by placing their second candidate debate at the Ronald Reagan Presidential Library, Republican officials put a spotlight on how far their party has moved from positions that made the 40th president a conservative icon.

Wednesday night's debate began with tributes to Reagan, but those sentiments don't change the reality of an evolving party.

The GOP has kept the social conservatism that made Reagan the preferred candidate for evangelical Christians — a constituency that now dominates many Republican primaries.

That's been clear throughout the campaign, as the candidates have sparred over how far to go to impose national bans on abortion, a goal sought by many Republican primary voters but opposed by a majority of Americans.

On multiple other issues, however — foreign policy, Social Security and Medicare, trade and immigration — the party of Donald Trump has sharply shifted away from that of Reagan.

The starkest change goes beyond policies to the party's underlying view of America's future.

Reagan's "undying faith that in this nation under God, the future will be ours" has little in common with Trump's grim warnings of a "nation in decline."

But the shift reflects a change in national mood, especially among the white voters who make up the vast majority of the GOP. Among white Americans, the share who view the country's future optimistically has dropped precipitously in recent decades, from roughly 3 out of 4 in 2000 to just 4 in 10 currently, according to the General Social Survey conducted by NORC at the University of Chicago.

In the current field of major candidates — the seven onstage Wednesday night and Trump, the consistent front-runner in polls who has so far declined to join 2024 debates — the clearest divide is between those who embrace that shift away from Reagan's outlook and those who resist it.

Former South Carolina Gov. Nikki Haley, former New Jersey Gov. Chris Christie and former Vice President Mike Pence have most clearly stuck to the pre-Trump, Reaganite consensus on major policy issues.

Businessman Vivek Ramaswamy and Florida Gov. Ron DeSantis have both tried to position themselves as younger versions of Trump. South Carolina's Sen. Tim Scott has mostly avoided drawing sharp contrasts with his rivals, and the seventh candidate onstage, North Dakota Gov. Doug Burgum, remains largely unknown to most voters.

"A lot of this is less about ideology than it is about temperament and approach," said GOP strategist Kevin Spillane, a strong Trump critic, in an interview before the debate. "Trump's campaign is not about policy. It’s about Trump and tone and temperament and message and vibe.” The effect, however, has been to "undermine" the pillars of traditional conservative policy, he added.

Not that anyone publicly acknowledges a change. Reagan remains a hero for many Republican voters: Four in 10 Republicans named him as the best president of the last 40 years in polling by the Pew Research Center this summer, slightly edging out the share who picked Trump.

And so the candidates praise Reagan even as several of them bury his legacy.

The clearest policy split with Reaganism involves the war in Ukraine.

"The concept underlying the Reagan Doctrine was aiding those who are willing to fight for their own freedom," said David Trulio, president of the Ronald Reagan Presidential Foundation and Institute, the private group that shares grounds with the publicly run library.

"That's a concept that's very directly applicable in the context of Ukraine, where Russia was an aggressor and the Ukrainians are willing to fight for their own freedom," Trulio said in an interview before the debate. "There has certainly been division — and those who disagree, I think that's a really critical issue for all of us to be listening for."

Those who disagree, as Trulio put it, include a majority of Republican voters. In a poll released this week by YouGov and the Economist magazine, 60% of Republicans sad they wanted aid to Ukraine cut, and 29% said aid should be eliminated entirely.

Prominent far-right Republicans, like Rep. Marjorie Taylor Greene of Georgia, have vowed to block more U.S. money for Kyiv even as traditional party figures, like Senate Republican leader Mitch McConnell of Kentucky, have pushed for more funds. That division has played a big part in blocking House Republicans from passing legislation to fund government agencies, leading to a likely shutdown starting this weekend.

Trump's peculiar admiration for Russian President Vladimir Putin has helped shift Republican opinion toward Russia. But more broadly, his denigration of NATO and other U.S. alliances and opposition to U.S. involvement overseas has revived isolationism, which was a major force in Republican politics before World War II and the Cold War. His "America First" catchphrase echoes a leading isolationist slogan from the late 1930s and early 1940s.

Last month in the first GOP debate, some of the most heated divisions involved Ukraine, with Ramaswamy asserting that U.S. help for Kyiv was "driving Russia further into China’s hands," and Haley turning on him and saying, “You have no foreign-policy experience, and it shows.”

GOP traditionalists also differ from Trump on government spending, which may be most important when it comes to the two huge programs for retirees, Social Security and Medicare, which together account for about one-third of what Washington spends.

Before Trump, the GOP consistently called for efforts to hold down the cost of those programs, referred to in budget lingo as entitlements. In his 2016 campaign, Trump promised not to touch either program. In the current campaign, he has attacked several of his rivals, most notably DeSantis, for past congressional votes in favor of limits on entitlement spending.

Haley has most openly stuck with the pre-Trump view of entitlements.

“We need to slow the biggest drivers of our national debt. Democrats and Republicans don’t want to admit it, but Americans deserve the hard truth. Entitlement spending is unsustainable. We need reform,” she said last week in what her campaign billed as a major economic policy speech in New Hampshire. Among other steps, she called for raising the retirement age for future retirees.

Her deft advocacy of such positions has helped Haley consolidate support among the party's traditionalist wing. But while the debate onstage may be lively, there's not much question which side is winning in the contest between Reaganism and Trumpism.

The Reaganite trio — Haley, Christie and Pence — collectively draws support from about 1 in 7 Republican voters nationwide, according to the average of polls maintained by the FiveThirtyEight website. Trump alone consistently has the support of more than half.

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This story originally appeared in Los Angeles Times.