SEATTLE — Election officials from Seattle's King County convened Thursday to begin counting more than 700 mistakenly discarded ballots that were expected to widen Democrat Christine Gregoire's lead in Washington's incredibly tight race for governor.

On Wednesday, Gregoire moved ahead of Republican Dino Rossi for the first time in the roller-coaster race, seizing a mere 10-vote lead out of 2.9 million ballots cast statewide, after the results of the latest recount were reported.

Earlier that day, the state Supreme Court ruled that King County, the state's most populous county and a Democratic stronghold, could also count 732 belatedly discovered ballots. County officials planned to announce those results Thursday afternoon.

The Republicans have refused to concede the race, raising the possibility it could drag on for weeks. Gregoire, for her part, urged Rossi to abide by the results of the recount.

"We've got huge issues facing the state, and we need to get on with it," she said Wednesday. "Whoever is governor is going to have a challenge of bringing the state together."

Shortly before the King County canvassing board met on Thursday, the Republicans countered with their own claims of overlooked ballots, submitting affidavits from 91 people who says they voted for Rossi and believe their ballots were erroneously rejected.

But Dean Logan, the county's elections director, said those ballots would not be considered because they were properly rejected.

Republican officials said they will also blanket the state over the next week looking for Rossi voters whose ballots were mistakenly disqualified. And they said they knew of military voters overseas who say they never received their ballots.

Secretary of State Sam Reed, a Republican, is set to certify the election results Dec. 30. Once the election is certified, the GOP may pursue a legal challenge.

Gregoire, 57, a three-term attorney general, was the favorite going into the election against Rossi, 45, a real estate agent and former state senator. But seven weeks after Election Day, the race has gone through three counts, including a machine recount and then a hand recount.

Rossi led by 261 votes in the first count after Election Day. The machine recount showed him winning by a mere 42.