LAS VEGAS, Nev. (CBS) —  Nine presidential candidates participated in a prime-time Tuesday night debate, live from Las Vegas, Nevada.

It was the final Republican presidential primary debate of 2015, a critical event that will help shape the contest heading into the Iowa caucuses.

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Who do you think won?

Candidates are displayed in alphabetical order by last name.

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Donald Trump headed into the debate with more support than ever: 41-percent nationally among likely republican voters according to a new Monmouth University poll and leading the next candidate, Senator Ted Cruz , by 27 points.

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The polling began last Thursday, just days after Trump announced his plan to temporarily ban Muslims from entering the U.S.