Hillary Clinton leads Sen. Bernie Sanders, I-Vermont, by 9 percentage points in Iowa, according to a Monmouth College/KBUR-AM survey released Thursday.

Nearly 48 percent of likely Democratic caucus goers said they back Clinton for president while about 39 percent said they support Sanders.

About 7 percent said they back former Maryland Gov. Martin O'Malley and about 6 percent said they remain undecided.

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The poll comes just about a week before the Iowa caucuses on Feb. 1.

Sanders, meanwhile, has been expanding his lead over Clinton in New Hampshire, which will hold the first-in-the-nation primary on Feb. 9. A CNN/WMUR survey released Tuesday, for example, found Sanders is now leading by 27 percentage points in the Granite State. Another survey by Monmouth University from earlier this month showed Sanders was 14 percentage points ahead of Clinton in New Hampshire.

The latest poll surveyed 570 likely Democratic caucus goers between Jan. 18 and 19, after Sunday's Democratic debate, with a 4.1 percentage point margin of error.