Story highlights Clinton is leading Sanders 42% to 40%

Uncommitted voters make up 14% of the caucusgoers, according to the poll

Washington (CNN) Hillary Clinton's edge over Bernie Sanders has shrunk to just two percentage points in Iowa, according to new Bloomberg/Des Moines Register poll of likely Democratic Iowa caucus voters released Thursday.

Clinton tops Sanders 42% to 40%. Ex-Maryland Gov. Martin O'Malley was at 4% in the new poll.

Last month, a Bloomberg/Des Moines Register poll found Clinton was ahead of Sanders by 9 points, 48% to 39%.

In the new poll Thursday, 14% of those surveyed say they are uncommitted. In December, 8% were uncommitted.

Support for the candidates mirrors that in other polls. Sanders is strongest among younger voters, while Clinton is leading with older voters and women.

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