In a Monmouth University poll released Monday, the Texas senator leads Trump 24 percent to 19 percent among likely caucus-goers. His support in the survey has spiked 14 percentage points since October.
Monmouth pollster Patrick Murray partly attributed Cruz's rise to a collapse in support for retired neurosurgeon Ben Carson, whose numbers have dropped by 19 points since two months ago. Cruz has also been helped by the recent endorsement of U.S. Rep. Steve King of Iowa, which Murray said "certainly put a stamp on the Cruz surge in Iowa."
Cruz is also performing strongly among evangelical voters, who tend to make up roughly half of the Iowa GOP caucus electorate. The survey found Cruz beating Trump 30 percent to 18 percent among evangelical voters.
Besides Cruz and Trump, the only other candidates who registered double-digit support in the poll were U.S. Sen. Marco Rubio of Florida at 17 percent and Carson at 13 percent.
Campaigning Monday in South Carolina, Cruz called the survey "very encouraging."
"We’re seeing a continuation of the energy and momentum that has been gradually and steadily building in Iowa and South Carolina and New Hampshire and all across the country," Cruz told reporters after a town hall in Greenville. "From the beginning, the approach of this campaign was to build a campaign on a foundation of stone and not a foundation of sand, following the biblical principle of systematically unifying and bringing together conservatives, and we’re seeing that happening powerfully in the state of Iowa."
"We’ve got a long way to go, but it's certainly true that going up is better than going down," Cruz added.
The Monmouth poll was done by telephone Thursday through Sunday with 425 Iowa Republicans considered likely to participate in the Feb. 1 caucuses. The survey has a margin of error of +/- 4.8 percent.