With Washington state in the middle of a recount of its amazingly close governor's race, election officials in Seattle's King County (search) entered a warehouse Friday and found a plastic tray containing 150 misplaced ballots.

The discovery brings the number of belatedly discovered ballots to 723 in the heavily Democratic county — potentially enough to swing the election to Democrat Christine Gregoire (search).

Republican Dino Rossi (search) won the Nov. 2 election over Gregoire by 261 votes in the first count and by 42 after a machine recount of the 2.9 million ballots cast. On Thursday, with every county except King, Pierce and Spokane reporting, Rossi had pulled ahead by 74 votes.

King County Elections Director Dean Logan told The Seattle Times that the ballots in the tray, like the 573 other ballots found earlier this week, were mistakenly rejected because there was a problem with how the voters' signatures had been scanned into the county's computer system. The tray apparently was left behind and forgotten in the warehouse, Logan said.

Election workers, along with observers from the political parties, searched the locked cage inside the warehouse.

Officials became curious because none of the 573 ballot envelopes contained names beginning with the letters A or B, and only two started with C, The Times reported. That prompted Friday's search.

King County election officials want to count the ballots, which they say are valid votes. Republicans want those ballots to stay rejected — or at the very least, they want King County to investigate further before adding them to the mix.

"We want to get some answers about these very suspicious ballots," Republican State Party Chairman Chris Vance said Thursday.

The GOP planned to ask a judge Friday to block King County from taking the newly discovered ballots out of their outer envelopes, which bear the voter's signature.

Vance said removing the envelopes would make it far more difficult to determine where the ballots came from, whether they were stored correctly and why they were not counted previously.