A new poll from Quinnipiac University shows Donald Trump leading in Iowa, while Ben Carson has seen a large drop.

The poll has Donald Trump with 28 percent, followed by Sen. Ted Cruz (R-TX) with 27 percent among likely Republican voters. Sen. Marco Rubio (R-FL) is in third place with 14 percent. Dr. Ben Carson is at 10 percent. All other Republican presidential contenders are under 5 percent.

The new poll shows a significant drop in support for Carson. In Quinnipiac’s October 22nd poll, Carson was leading by eight percentage points. Much of his support seems to have shifted to Cruz.

The poll also found that terrorism was on the top of of the list of priorities for likely Republican voters, with 30 percent of likely Republican caucus voters saying it’s the most important issue for them. The second most important issue for voters is economy and jobs, with 21 percent. In Quinnipiac’s November 24 poll, economy and jobs was the number one priority.

When asked which candidate can handle terrorism the best, 33 percent said Trump and 24 percent said Cruz. Only 9 percent of voters think Rubio would be the best at handling terrorism.

Peter A. Brown, assistant director of the Quinnipiac University Poll said, “With seven weeks to go until the voting, whether Trump or Sen. Ted Cruz or any of the other candidates prevails will likely be determined by which candidate has the best turnout operation – a subject about which everyone likes to speculate but is not measurable until caucus night February 1.”

The telephone survey was conducted from December 4 -13 in the state of Iowa with 847 likely Iowa Republican Caucus participants. The margin of error was 3.3 percentage points.