Sen. Hillary Rodham Clinton's potential Republican challengers are battling anonymity in their race for the GOP nomination, with nearly 80 percent of voters saying they don't know enough about either front runner to give a thumbs up or down, a new poll released Monday shows.

Kathleen Troia "KT" McFarland, a Reagan-era Pentagon official, was favored by 20 percent of likely Republican voters in the Siena College Research Institute poll. Former Yonkers Mayor John Spencer was the choice of 18 percent.

The remaining 63 percent said they didn't know who to support in the Sept. 12 primary.

When all the GOP respondents were asked if they had a favorable or unfavorable opinion of McFarland and Spencer, 79 percent said they didn't know enough about them to have an opinion.

The telephone poll of 413 likely Republican primary voters was conducted March 29 through April 3 and has a sampling error margin of plus or minus 5 percentage points.

The poll did not compare the GOP challengers to Clinton, although previous Siena polls and other independent surveys have found the former first lady with huge leads.

The anonymity factor also was evident for Republicans seeking to run for governor of New York this year. GOP incumbent George Pataki decided not to seek a fourth term and is eyeing a 2008 run for president.

Seventy-eight percent of GOP voters said they didn't know enough about former Massachusetts Gov. Bill Weld, running now in his native New York, to form a favorable or unfavorable opinion about him. Seventy-five percent of GOP voters said the same of former state Assembly Minority Leader John Faso.

Getting known in New York can be expensive — a major statewide television campaign can easily set a candidate back $1 million a week.

According to figures released Thursday, Clinton had $19.7 million at the end of March for her re-election effort, while McFarland had about $430,000 and Spencer about $340,000.

"At this point, the campaign is about raising money and winning the support of the grass roots and the leaders of the Republican and Conservative parties," said Kevin Collins, Spencer's campaign manager.

William O'Reilly, a spokesman for McFarland's newly started Senate campaign, said they had "come a long, long way in five short weeks."

"This is a motivated candidate with a motivated campaign team," he said. "We'll put in the work and let the results take care of themselves."