WASHINGTON -- Depending on which survey you read on Monday, businessman Donald Trump either is increasing his lead for the Republican presidential nomination in the first caucus state of Iowa or has fallen behind Texas Sen. Ted Cruz.

Call it a tale of two polls.

A CNN/ORC International poll had Trump with 33 percent support among likely Republican caucus goers. Cruz was second with 20 percent and retired neurosurgeon Ben Carson third with 16 percent. Florida Sen. Marco Rubio was fourth with 11 percent.

Cruz, on the other hand, led a Monmouth University survey of likely GOP caucus goers with 24 percent, followed by Trump with 19 percent, Rubio with 17 percent and Carson with 13 percent.

Here are six takeaways from the two surveys.

1. Here's why the polls differ.

The director of the Monmouth University Polling Institute, Patrick Murray, said the two surveys used different methods for determining who was likely to show up at the Republican caucuses next February.

Murray said his model projected a record turnout, albeit much fewer caucus goers than CNN expected. The bigger the turnout, the better for Trump, he said.

"The higher it goes, the better Trump does," Murray said. "That's what it really boils down to."

The CNN survey of 552 likely Iowa GOP caucus goers was conducted Nov. 28- Dec. 6 and had a margin of error of 4 percentage points. The Monmouth poll of 425 likely Iowa Republican caucus goers was conducted Dec. 3-6 and had a margin of error of 4.8 percentage points.

2. Either way, Cruz is surging.

Cruz's support in both polls is significant higher than it was earlier, whether he is in first or second place.

Cruz was in fourth place with 11 percent in a CNN poll released last month, and at 10 percent and tied for third place with Rubio in an October Monmouth poll.

A member of the Senate Armed Services Committee, Cruz was just behind Trump in the CNN poll, 30 percent to 21 percent, on which candidate was best able to handle foreign policy.

He trailed Trump by just 3 percentage points, 25 percent to 22 percent, in the CNN poll on the question of which candidate best represented the values of Republicans like yourself.

Cruz first moved into second place in Iowa in a Quinnipiac University poll, trailing Trump, 25 percent to 23 percent.

3. Trump shows no signs of faltering.

In the CNN poll, 52 percent said Trump was the candidate best able to handle the economy and 49 percent said immigration. He was judged the candidate best able to win the general election by 42 percent to 17 percent over Cruz and most effective at solving the country's problems by 36 percent to 17 percent over Cruz.

In terms of handling the Islamic State, also known as ISIS, Trump led, 41 percent to 18 percent over his closest competitor, Cruz.

4. Carson's 15 minutes of fame may be over.

Carson led Trump in Iowa in three October surveys. One of them was an October Monmouth poll where he led Trump, 32 percent to 18 percent. A CNN poll released last month gave Carson 23 percent in Iowa, just two points behind front-runner Trump's 25 percent.

Since then, as foreign policy and terrorism became more important to Republican voters, Carson's support diminished.

A sign of his troubles came at last Thursday's Republican Jewish Coalition presidential forum, when he mispronounced the name of the Palestinian group, Hamas, which is sworn to Israel's destruction and is designated as a terrorist organization by the U.S.

In the Quinnipiac poll of likely Iowa caucus goers, Carson led with 28 percent in October and fell to third place and 18 percent in November.

5. Christie's not going anywhere in Iowa.

Despite some prominent endorsements and some campaign appearances, Gov. Chris Christie remains far behind in Iowa, making the first primary state of New Hampshire that much more important. He polled 2 percent in the CNN survey, statistically unchanged from the 3 percent he had last month, and was at 2 percent in the Monmouth poll, again statistically unchanged from 1 percent in October.

6. Clinton remains in front.

Among likely Democratic caucus goers, former U.S. Secretary of State Hillary Clinton led Vermont U.S. Sen. Bernie Sanders, 54 percent to 36 percent, virtually unchanged from the last CNN poll. Former Maryland Gov. Martin O'Malley had 4 percent. By 77 percent to 18 percent, Democrats chose Clinton over Sanders as the candidate more likely to win the general election.

But when asked which candidate best represented Democrats like themselves, Clinton held just a 46 percent to 44 percent lead over Sanders.

That poll of 442 likely Democratic caucus goers had a margin of error of 4.5 percentage points.

Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant. Find NJ.com Politics on Facebook.