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Sen. Ted Cruz (R-Texas) has taken his first lead in a poll of a key nominating state.
A new Monmouth University poll published Monday had Cruz surging ahead of Donald Trump in Iowa, the first nominating state that can play a key role in launching insurgent presidential campaigns.
Among likely Republican voters in the state, Cruz garnered 24% support to Trump's 19% support. Sen. Marco Rubio (R-Florida) had 17% support in the poll, while retired neurosurgeon Ben Carson, who briefly surged ahead of Trump in the fall, is now down to 13%.
"This marks the first time Ted Cruz has held a lead in any of the crucial early states. As Ben Carson's stock has fallen, Cruz has been able to corral most of those voters," Patrick Murray, director of the Monmouth University Polling Institute, wrote in a press release.
Murray pointed to Rep. Steve King's (R-Iowa) recent Cruz endorsement as something that could be helping the senator's numbers, though the poll itself doesn't suggest much movement.
"Congressman King's endorsement may not be the primary reason for this swing, but it certainly put a stamp on the Cruz surge in Iowa," the pollster added.
Other polling experts say that while Cruz's surge in this Iowa poll appears to be consistent with other polls that show the senator slowly rising, it's too soon to declare a Cruz surge.
"We are just barely entering a period when these surveys start to be predictive," Princeton polling expert Samuel Wang told Business Insider on Monday.
"Rubio and Cruz have been on the rise in the last month or so. It's not clear whether Trump is fading, or if that's just up-and-down fluctuation."
University of Michigan polling expert Michael Traugott pointed out that Monmouth appeared to tweak its survey methods, which Traugott says could make Monday's poll slightly different than past Monmouth polls.
"The first thing I notice is that the sample size is only 425, with a [margin of error] of 4.8 (5)% points," Traugott said in an email. "They also modified the sample design from the previous poll to include some general election voters as well as caucus participants. This has two consequences: The differences between the leading candidates is unclear (MOE) and the trend from the previous poll is not easily discernible (design shift)."
Other Republican candidates appear to be increasingly wary of Cruz as he's steadily climbed in state and national polls.
Rubio has repeatedly criticized Cruz over his support for the USA Freedom Act, which curbed the National Security Agency's telephone metadata surveillance program exposed by former contractor Edward Snowden.
"I stand strongly on behalf on the ability of this government to gather intelligence on our adversaries and our enemies," Rubio told Fox's Greta Van Susteren last week. "Those keep us safer. And there are Republicans — including Sen. Cruz — that have voted to weaken those programs. That's just part of the record. It's nothing personal."
Though Cruz has promised not to attack his fellow Republican candidates during the campaign, he hasn't shied away from the fight with Rubio, charging that the Florida senator is nervous about Cruz's rise in the polls.
"I think the reason that Rubio's allies have resorted to false attack ads is they are very, very nervous about our surge in the polls, about the fact that conservatives are uniting behind our campaign," Cruz told radio host Hugh Hewitt last week.
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