This combination of 2023 photos shows, from left, former President Donald Trump, Florida Gov. Ron DeSantis, former U.N. Ambassador Nikki Haley, former Vice President Mike Pence and South Carolina Sen. Tim Scott. Charlie Neibergall, Meg Kinnard | AP

Former President Donald Trump holds a double-digit lead over his closest rival, Florida Gov. Ron DeSantis in a major new poll of likely Republican caucusgoers in Iowa released Monday. The state will hold the first nominating contest of the 2024 GOP presidential primary race on Jan. 15. Trump garnered the support of 42% of respondents, while DeSantis came in second with 19%. Trump's 23-point lead over DeSantis is the largest GOP caucus advantage recorded by the poll since the 2000 primary, when George W. Bush notched a 30-point advantage. After Trump and DeSantis, no other candidate scored double digit support. Scott won 9%; former Vice President Mike Pence and former South Carolina Gov. Nikki Haley both came in at 6%; former New Jersey Gov. Chris Christie was at 5%; and 4% back Vivek Ramaswamy, an entrepreneur and political newcomer.

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But Trump's advantage is still not ironclad, according to the joint survey conducted by the Des Moines Register, NBC News and Mediacom. Fully 52% of respondents said they had not yet decided who they would support, while 40% said they were certain. With about five months to go before the Iowa caucuses, that uncertainty could be key to giving candidates like DeSantis and South Carolina Sen. Tim Scott an opening — especially as Trump's unprecedented criminal charges in four separate cases increasingly dominate his campaign's message. When asked who their second choice would be, a 20% plurality picked DeSantis, followed by Scott at 15% and 12% for Ramaswamy. A further 29% of respondents said they were actively considering Haley — the same percentage who said they were actively considering Scott.

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Nearly two-thirds of respondents also said they have a favorable view of Trump, a virtual tie with DeSantis. Trump touted the survey results in a social media post Monday morning, while declaring that he had obtained $28 billion from China for U.S. farmers — an assertion that fact-checkers have rated false. In an overture to Iowa voters, Trump also asserted without evidence that he "saved" ethanol and popular entitlement programs. The survey, conducted by Iowa pollster J. Ann Selzer, questioned 406 likely Republican caucusgoers from Aug. 13-17. It has a margin of error of 4.9 percentage points. While Trump and DeSantis share a similar overall approval in the state — 63% for Trump and 61% for DeSantis — the Florida governor's support appears to be much shakier than the former president's. Of the 40% of likely GOP caucusgoers who said they had made up their minds on who to support, two-thirds picked Trump, versus 31% for DeSantis.

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