Dec. 26 (Bloomberg) -- Senator Hillary Clinton of New York widened her lead over Democratic rivals in a poll of people who plan to participate in the Iowa caucus.

Clinton was supported by 34 percent of the people surveyed by the American Research Group, followed by John Edwards with 20 percent and Barack Obama with 19 percent. The poll was taken Dec. 20-23. In a poll taken Dec. 16-19 by the same group, Clinton led with 29 percent to 25 percent for Obama and 18 percent for Edwards.

Clinton led Senator Obama of Illinois among women, 38 percent to 21 percent, unchanged from a week ago, according to the American Research Group. Obama lost ground among men, the survey showed, trailing with 16 percent to 28 percent for Clinton and 27 percent for Edwards, the Democratic vice presidential nominee in 2004. A week ago, Obama was at 27 percent among men.

Among Republicans, former Arkansas Governor Mike Huckabee's lead narrowed slightly. In the latest poll, he was supported by 23 percent of those questioned to 21 percent for former Massachusetts Governor Mitt Romney, 17 percent for Senator John McCain of Arizona and 14 percent for former New York Mayor Rudolph Giuliani. The earlier survey showed Huckabee with 28 percent support, followed by McCain at 20 percent and Romney at 17 percent.

The poll, which has a margin of error of plus or minus four percentage points, was conducted by telephone among a random sample of 600 likely Iowa caucus-goers.

To contact the reporter on this story: Holly Rosenkrantz in Washington at hrosenkrantz@bloomberg.net;

Last Updated: December 26, 2007 12:07 EST