Former Secretary of State Hillary Clinton has a double-digit lead in Iowa, besting Sen. Bernie Sanders, I-Vermont, by 22 points in a new Monmouth University poll of likely Iowa Democratic caucus goers.

Fifty-five percent of those surveyed say they support Clinton, and 33 percent say they support Sanders. Former Maryland Gov. Martin O'Malley, the only other candidate remaining in the Democratic race, has 6 percent support.

Clinton's lead is especially pronounced among female voters (61 percent support her versus 27 percent who support Sanders) and older voters (63 percent versus 26 percent). She only has a five-point lead over Sanders among male voters and Sanders still maintains a lead among respondents under age 50: 48 percent say they support him, versus 38 percent who support Clinton.

Monmouth adjusted this month's poll to include regular general election voters and new registrants. A previous poll from October found that people who had participated in the Democratic caucus in the past supported Clinton by a margin of 65 percent to 24 percent. That lead has shrunk in the current poll, with previous caucus participants only supporting her by a margin of 57 percent to 30 percent.

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Clinton also leads by 22 points among Democrats who haven't participated in the caucuses before but plan to do so this February. She and Sanders are tied with 45 percent support each among people who say they will change their party registration in order to vote in the Democratic caucuses. That's about 14 percent of the total pool of people.

"The core of this electorate is going to be registered Democrats. And Clinton appears to have that group firmly in her corner," said Patrick Murray, director of the independent Monmouth University Polling Institute in West Long Branch, NJ.

Monmouth also tested to see how a huge in turnout would affect Clinton's lead. Even with 200,000 voters participating in the Democratic caucus - which would come close to the all-time high of 240,000 in the 2008 Democratic primary - Clinton would still lead Sanders by 13 points. That led Murray to conclude that Sanders' chances of winning in Iowa remain "formidable."

At the end of the day, the likely Democratic caucus goers seem like they will be happy with whoever the nominee is. Nearly nine in 10 poll participants said they would be enthusiastic or satisfied with Clinton as the nominee; eight in 10 said the same of Sanders.