Greenville -- The Democratic race for governor appeared to tilt toward Camden state Sen. Vincent Sheheen on Friday, though nearly a third of likely primary voters remained undecided.

That large, hanging slice of voters could be a sign many simply aren't familiar with any of the three candidates, who in turn may be conserving their advertising cash for a general election battle with Republicans, said Danielle Vinson, a political science professor at Furman University.

Sheheen captured 30 percent of likely Democratic voters with state Superintendent of Education Jim Rex getting 22 percent and Charleston Sen. Robert Ford snagging 4 percent, according to Rasmussen Reports, which surveyed 404 likely voters and reported a margin of error of 5 percentage points, plus or minus.

Unlike the high-profile endorsements and disputes among GOP candidates, there hasn't been much to startle voters into looking at Democrats. None are from the Upstate, and none are widely known statewide although Rex has held statewide office for less than a term, Vinson said.

Sheheen and Rex were tied in the same poll two months ago at 16 percent apiece, with Ford at 12 percent.

When asked about his fall-off in support, Ford spokesman O'Neal Compton said Friday the poll is "wildly inaccurate" in part because the kinds of people who support Ford often don't tell pollsters whom they are backing.

Ford's campaign has made a point of noting that he doesn't have the cash for television ads and internal polling, but Compton said public response to Ford around the state has been "tremendous."

Rex's campaign spokesman, Zeke Stokes, said the poll confirms a tight race, and that Rex has a good shot at reaching the large numbers of undecided voters.

Sheheen spokesman Trav Robertson said it is the first time his campaign has led in a public poll, showing a strategy of media ads and on-the-ground communication is paying off and voters like what they see.

Doug Woodard, a Clemson University political scientist, said Rex has been hurt by his decision not to run as many TV ads, while Sheheen is developing a low-key, likable approach that could appeal to independent voters in the general election.

Robertson said an undecided voter swath of 32 percent could "drastically sway" the primary, and that there is more work to do.