The Democratic race in the key early primary state of New Hampshire has tightened with Barack Obama gaining ground on front-runner Hillary Rodham Clinton, according to a new poll released Sunday.

On the Republican side, support for former Massachusetts governor Mitt Romney has grown slightly since the last poll of New Hampshire voters in October, according to the Marist College Institute for Public Opinion.

Among Democrats, Clinton, the New York senator, led with 36 percent, followed by Illinois senator Obama with 25 percent. Former North Carolina senator John Edwards had 14 percent, and New Mexico Gov. Bill Richardson 6 percent.

Romney led all Republicans with 33 percent, followed by former New York Mayor Rudy Giuliani with 22 percent and Arizona Sen. John McCain with 13 percent. U.S. Rep. Ron Paul and former Arkansas Gov. Mike Huckabee each had 7 percent, with former Tennessee senator Fred Thompson at 5 percent.

In the October poll, Clinton led Obama by 40 percent to 20 percent, while Romney had 25 percent to Giuliani's 21 percent.

The New Hampshire primary in early January is one of the first key tests in the presidential nominating process, serving to provide momentum to the front-runners and winnow the field.

The poll found that nearly two-thirds of Clinton's supporters strongly support her, while roughly half of Obama's say the same. About half of Romney's and Giuliani's backers express firm support.

Terrorism, the economy and immigration are the top concerns cited by likely Republican voters, while Democrats name the war in Iraq, the economy and health care.

The poll involved telephone interviews conducted Nov. 2-6 with 458 likely Democratic voters and 372 likely Republican voters. The margins of sampling error were 5 percentage points for Democrats and 5.5 points for Republicans.