Ted Cruz has soared ahead of Donald Trump in a new Iowa poll released on Saturday, opening up a 10-point lead in the critical first-in-the-nation voting state. The poll of 400 likely Republican caucus-goers was conducted between December 7 and 10, after Trump called for a ban on allowing Muslim immigrants into the U.S. It has a margin of error of plus or minus 4.9 percentage points. For Cruz, the poll represents a 21-point jump from a survey conducted by the two outlets in October: The Des Moines Register and Bloomberg Politics poll released on Saturday finds Cruz commanding 31% of likely Republican caucus-goers in the state, 10 points ahead of Trump, who received 21%. Cruz and Trump will face off Tuesday in Las Vegas at the next Republican presidential debate, which CNN will sponsor.