Sen. Hillary Rodham Clinton is maintaining big leads over potential Republican re-election opponents but would not fare as well among New York voters if she were to face former New York City Mayor Rudolph Giuliani in a 2008 presidential race, pollsters reported Monday.

The poll, by Siena College's Research Institute, found the Republican Giuliani leading the former first lady 48 percent to 42 percent among registered voters asked about a hypothetical 2008 presidential matchup. The poll has a sampling error margin of plus or minus 4 percentage points.

In another possible 2008 matchup, Republican Sen. John McCain of Arizona was favored by 46 percent of New York voters, compared to 42 percent for Democrat Clinton.

Other recent New York polls have found similar results.

The relatively strong showing by Giuliani and McCain against Clinton "will certainly put pressure on New York's junior senator to try and run up a big victory in her re-election battle this fall," said Steven Greenberg, a spokesman for Siena's polling operation.

The poll found 57 percent of New York voters saying they would vote in November to re-elect Clinton to the Senate and 38 percent saying they would prefer someone else, unchanged from a June poll by the Albany-area research institute.

Also unchanged from earlier Siena polls were Clinton's large leads over potential GOP opponents: 58 to 32 percent against former Yonkers Mayor John Spencer and 58 to 28 percent ahead of Reagan-era Pentagon official Kathleen Troia "KT" McFarland.

Recent polls have shown Spencer with a slight edge over McFarland for the state's Sept. 12 primary.

Siena's telephone poll of 623 registered voters was conducted July 31 to Thursday.