Republican U.S. presidential candidate businessman Donald Trump (L) reaches out to shake hands with Senator Ted Cruz as former Governor Jeb Bush (R) looks on before the start of the Republican presidential debate in Las Vegas, Nevada December 15, 2015. [Photo/Agencies]

Trump, who also backed closing parts of the Internet used by Islamic State militants, has dominated the last few weeks of the campaign with his call for a total ban on Muslims entering the United States, following a married couple's Dec. 2 massacre of 14 people in San Bernardino, California, inspired by Islamic State.

Most of Trump's Republican rivals, as well as officials and leaders in the United States and around the globe, have criticized Trump's proposal although many of his supporters have voiced sympathy with his views.