A week after heaping praise on Donald Trump before a speech at Liberty University, the school's president Jerry Falwell Jr. is officially throwing his support behind the Republican presidential candidate.

The backing comes just days before the lead-off caucuses in Iowa. Trump's top challenger there is Ted Cruz, the son of an evangelical pastor.

Cruz launched his campaign at Liberty and is banking on support from Christian conservatives to push him toward the nomination.

Falwell Jr. praised Trump in an introduction at the school last week, comparing Trump to his late father.

The campaign already had been using Falwell's remarks in a radio ad.

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