GREENVILLE, S.C. — In an election that Republicans have long seen as a chance to put forward new stars with a fresh and broadly appealing conservative vision, the party is instead at risk of tearing itself apart over its past as it heads into the thick of the primary season.

A day after a debate marked by personal, petty exchanges, Republicans were grappling with their core beliefs on a host of issues, as well as the image they were broadcasting to the country.

The infighting was ignited at the debate Saturday night by front-runner Donald Trump, who was unrelenting in his criticism of both how well former President George W. Bush kept America safe before and after the Sept. 11, 2001, attacks and of hawkish Republican worldview in general.

The foreign policy fracas is only the latest row among 2016 candidates over many of the basic tenets that have guided Republican and conservative thinking since the Reagan years, from free trade to the extent to which the federal government should be involved in providing health care for its poorest citizens.

Trump reiterated threats to use tariffs on imported goods to punish corporations that leave the United States, while Ohio Gov. John Kasich defended his decision to accept an expansion of Medicaid in his state as a humane step in line with conservative goals.

Trump was unapologetic Sunday, saying he is a truth-teller and that the majority of Americans would heed his call.

“The war in Iraq has been a disaster,” Trump said Sunday on CBS’s “Face the Nation.” “It started the chain of events that leads now to the migration, maybe the destruction of Europe. (Bush) started the war in Iraq. Am I supposed to be a big fan?”

Todd Harris, a senior adviser to Sen. Marco Rubio of Florida, echoed the sentiment of many when he said after the debate that Trump “was at war with the Republican Party.”

Fresh off his win in the New Hampshire primary, a poll released Sunday by CBS News showed Trump surging ahead of Saturday’s South Carolina primary. The survey showed Trump with the backing of 42 percent of Republican voters, more than double the support of his closest rival, Sen. Ted Cruz of Texas. The poll was taken before the debate and the ensuing fallout, which many Republicans predicted would limit Trump’s appeal going forward.

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