With 42 percent of the precincts reporting, Gregoire had 51 percent of the vote, compared to Rossi's 49 percent, CNN said.
Gregoire won her 2004 race against Rossi by 133 votes out of 2.8 million ballots cast, making it the closest gubernatorial race in U.S. history, the report said.
PolitickerWA.com reported that while the race has been called by several media outlets, Rossi was not prepared to concede.
"At this hour, fewer than 50 percent of ballots have been counted statewide. We saw in 2004 and again in the primary this year that later votes cast and counted trended heavily toward Dino Rossi," said Rossi spokeswoman Jill Strait. "If that happens again in this general election the results will change. The Rossi campaign simply does not feel that we are in a position to know who will win."