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Three polls on the Colorado governor's race came out last week, and they showed three very different results.

One had Republican Bob Beauprez up by 10 points; another found the race is very close, with Democratic Gov. John Hickenlooper leading by a small margin; and the third put Hickenlooper up by seven points.

They illustrate how difficult it is to get accurate polling results in Colorado, according to Harry Enten, a senior political analyst and writer at FiveThirtyEight, a website founded by Nate Silver, who rose to national prominance after closely calling the 2012 presidential election, that crunches numbers in politics, sports, and economics.

Enten says this was true in 2010, when just before the Senate election between Michael Bennet and Ken Buck, polls showed Buck in the lead. Bennet won the seat by a point. And in 2012, polls showed President Obama barely winning in Colorado, or not winning at all. He took the state by five points.

Enton says getting accurate poll results in Colorado is difficult, becuase of the large number of Latino voters, who can be hard to reach, and the high percentage of residents that only have cell phones.

Additionally, Enten says there are more polls funded by partisan groups than in years past, which can make certain polls unreliable. The poll last week finding Hickenlooper up by seven was backed by the progressive group Project New America.

He also says this year is particularly hard to predict, because it's the first major election since Colorado started mailing ballots to every registered voter. Nationally, a divided government, with the House controlled by Republicans and the Senate and White House controlled by Democrats, means an anti-incumbency vote isn't guaranteed to hurt one party more than another.