RENO -- Republican Rudy Giuliani and Democrat Hillary Rodham Clinton hold leads over their party presidential rivals in Nevada, according to a statewide poll released Sunday.

In head-to-head matchups in the general election, the survey found that Giuliani was favored by 46 percent to Clinton's 38 percent, and he had 44 percent to Illinois Democratic Sen. Barack Obama's 42 percent.

The poll of 600 voters was conducted Tuesday through Thursday by Research 2000 for the Reno Gazette-Journal and KRNV-TV. It has a margin of error of plus or minus 4 percentage points.

In the GOP field, the survey found that Giuliani, former New York City mayor, was backed by 38 percent to Arizona Sen. John McCain's 18 percent, former House Speaker Newt Gingrich's 13 percent and former Massachusetts Gov. Mitt Romney's 4 percent.

Former Nevada Gov. Kenny Guinn has thrown his support behind Romney's presidential bid, his campaign said Sunday.

Guinn, who left office in December, will lead Romney's Nevada finance steering committee, along with Barbara Vucanovich, a former congresswoman from Northern Nevada.

Among Democrats, New York Sen. Clinton was supported by 32 percent to Obama's 20 percent. Former Vice President Al Gore and former North Carolina Sen. John Edwards each had 11 percent, while New Mexico Gov. Bill Richardson and retired Gen. Wesley Clark each had 2 percent.

In other possible matchups in the general election, McCain had 44 percent to Clinton's 39 percent, while Giuliani had 46 percent to Edwards' 40 percent and Giuliani had 45 percent to Gore's 42 percent.

During a weekend visit to Reno, Giuliani said the poll results were not "too relevant right now" because the primaries and caucuses are still nearly a year away.

Clinton spokesman Blake Zeff said the numbers were encouraging for Clinton but the election was a long way away.

Nevada moved its Democratic presidential caucuses to Jan. 19, between Iowa's first-in-the-nation caucus and the New Hampshire primary.

Nevada Republicans followed suit last week by announcing plans to move up their caucuses to Feb. 7.