State Highlights

The vast majority of the ballots are cast by mail in Washington and were still being counted on Wednesday, but Senator Patty Murray, a Democrat, held a thin edge over Dino Rossi, a Republican former state senator who twice lost bids to become governor.

Exit polls showed that Ms. Murray was weaker with almost all demographic groups than in her previous re-election race. Only a slender majority of voters said they supported President Obama’s job performance. Voters who identified themselves as moderates supported Ms. Murray. Mr. Rossi had attempted to paint Ms. Murray, who has a long record of bringing federal dollars to state projects, as a spendthrift liberal. Ms. Murray defended her record and countered that Mr. Rossi would bankrupt America by giving tax breaks to the rich.

Mr. Rossi was not able to capitalize on strong opposition to a ballot measure that would have imposed a state income tax in Washington.

The measure, which was supported most famously by the father of Bill Gates, would have imposed the tax on the wealthiest 2 percent and would have reduced property taxes for everyone. But it was defeated, as middle-class voters feared that over time, the income tax would be imposed on a wider swath of the population.

Republicans picked up one Congressional seat in the southern part of the state.

MIGUEL HELFT