The Seattle Post-Intelligencer said Thursday Kerry sent the money to help fellow Democrat Christine Gregoire pay for a second recount of the Nov. 2 gubernatorial ballots.
Republican Dino Rossi was certified the winner by 42 votes. Gregoire has refused to concede.
After a mandatory machine recount shrunk Rossi's lead from 261 votes to 42 votes, Gregoire said she considered the race a tie and promised to make sure every vote cast would be counted.
Even with Kerry's substantial donation, however, Gregoire and the Democrats have not yet raised the $700,000 they need to put up in advance before election officials can begin a statewide hand recount.
A state party spokesman said the Democrats have $500,000 on hand, including Kerry's contribution, and have requested $200,000 from the Democratic National Committee.