MANCHESTER, New Hampshire (CNN) -- With Tuesday's New Hampshire primary fast approaching, Sen. Barack Obama has opened a double-digit lead over Sen. Hillary Clinton in the state, a CNN-WMUR poll found Sunday.

Obama, the first-term senator from Illinois who won last week's Iowa caucuses, led the New York senator and former first lady 39 percent to 29 percent in a poll conducted Saturday and Sunday -- a sharp change from a poll out Saturday that showed the Democratic front-runners tied at 33 percent.

Support for former Sen. John Edwards, who edged out Clinton for second place in Iowa, dropped from 20 percent in Saturday's poll to 16 percent.

On the Republican side, Sen. John McCain leads former Massachusetts Gov. Mitt Romney by a narrower margin -- 32 percent to 26 percent, the survey found. Former Arkansas Gov. Mike Huckabee -- whose upset win in Iowa came after being outspent by millions of dollars by Romney -- passed former New York Mayor Rudy Giuliani to gain third place.

In Saturday's poll, Giuliani had 14 percent and Huckabee had 11 percent; those numbers were reversed on Sunday.

The results suggest that Huckabee's win in Iowa, which saw him win strong support among evangelical Christian voters, is giving him momentum in more secular, libertarian-oriented New Hampshire, CNN Political Analyst Bill Schneider said.

Among other Republicans, anti-war Texas congressman and onetime Libertarian Party presidential nominee Ron Paul was in fifth place at 10 percent in the poll, with Rep. Duncan Hunter of California and former Sen. Fred Thompson of Tennessee both at 1 percent.

The poll, conducted by the University of New Hampshire, surveyed 341 Democrats and 268 Republicans likely to vote in Tuesday's New Hampshire primary. It had a sampling error of 5 percentage points. CNN Polling Director Keating Holland said. "In December, 45 percent thought Clinton had the best chance of beating the GOP nominee. But in Saturday's poll, Clinton and Obama were tied on that measure, and now Obama has a 42 percent to 31 percent edge over Clinton on electability."

And CNN Senior Political Analyst Bill Schneider said the poll "strongly suggests an Obama surge in New Hampshire. Obama's gaining about three points a day, at the expense of both Clinton and Edwards," Schneider said. "Obama's lead has now hit double digits going into the home stretch."

New Mexico Gov. Bill Richardson ranked fourth among the Democratic contenders with 7 percent, while Ohio Rep. Dennis Kucinich trailed at 2 percent. Former Alaska Sen. Mike Gravel had less than one half of 1 percent support.

Crucial to the outcome in New Hampshire are the state's independent voters, who make up around 40 percent of the electorate, and who can vote in either party's primary. The poll indicates that a growing number of registered Independents say they will vote in the GOP contest, which is a switch from just a month ago.

"That should be bad news for Obama, who was generally considered the favorite of Independents, but after the Iowa caucuses the Illinois senator has been building his support among registered Democrats and now leads Clinton among registered Democrats as well as Independents," says Holland.

Obama also appears to be pulling even with Clinton among women, a voting bloc that she once dominated in the polls. And when asked which candidate has the best chance of beating the Republican presidential nominee, likely Democratic primary voters now choose Obama over Clinton 42 percent to 31 percent.

That's a dramatic reversal from the last CNN/WMUR New Hampshire poll taken after Christmas and just before the Iowa caucuses, when Clinton beat Obama in electability by a two to one margin.