Gilmore's Aides Confident He's Ahead

But both campaigns are essentially guessing at their level of support. Many of the local GOP committees have not released final delegate lists, meaning the campaigns are making assumptions based on whom they saw at the local meetings.

Adding to the uncertainty, some delegates may be able to cast as many as 25 separate votes for the same candidate while others get just fractions of a vote. The discrepancy arises because each county and city is given a certain number of votes -- based on the performance of recent Republican candidates in those areas -- regardless of how many people sign up to be delegates.

"Anyone who tells you they have a vote count right now is fooling you," said GOP strategist J. Kenneth Klinge, a Marshall supporter from Northern Virginia.

Candidates also have to make sure the delegates, who can change their mind about who they want to support, show up at the convention in Richmond.

Patrick M. McSweeney, a former chairman of the Virginia Republican Party, said the campaign will continue right up to the convention.

"There will probably be negative charges that have to be responded to and there will be disinformation campaigns and some persuasion involved," McSweeney said. "But most of the effort is turnout."

Because there is no way to determine the outcome, there are often upsets at conventions. Social conservatives have also tended to dominate conventions.

In 1993, Michael P. Farris surprised many in the party by defeating Bobbie G. Kilberg for the nomination for lieutenant governor. Farris, a home-schooling advocate who lost the general election to Donald S. Beyer Jr., relied on a network of families that home school their children and abortion opponents.

Marshall, who also home-schooled his five children, is employing a similar strategy against Gilmore. Marshall has been critical of Gilmore over his support for abortion rights until the eighth week of a pregnancy. Marshall was also the co-sponsor of a constitutional amendment, which voters approved in 2006, to ban gay marriage and civil unions.

"We are working from the grass roots up," said Steve Waters, Marshall's campaign manager. "A lot of our people are working beneath Gilmore's radar."

Gilmore supporters said he also has deep roots in the conservative movement. Even though he makes no apologies for more moderate views on abortion, Gilmore said he fought for parental notification for minors seeking an abortion and helped enact legislation to ban late-term abortions.

"There is an awful lot of pro-life leaders in the state of Virginia who look at Jim Gilmore's record and say he accomplished a lot of things to help the pro-life cause so they are very comfortable with Gilmore," Marcus said.