The 2010 United States Senate election in Washington was held on November 2, 2010, alongside other elections to the United States Senate in other states as well as elections to the United States House of Representatives and various state and local elections. Incumbent Democrat Senator Patty Murray won re-election to a fourth term by a margin of 52.4% – 47.6% over Republican Dino Rossi, who had run for governor in 2004 and 2008. This was the last U.S. Senate election in Washington where the margin of victory was single digits.

Top-two primary election

Candidates

Democrats

Republicans

Others

Polling

Results

General election

Candidates

The top 2 candidates from the blanket primary advanced to the general election.

Campaign

Rossi heavily criticized Murray for her support of the 2009 economic stimulus package; however, Rossi's economic promises are nearly identical to those of President Bush who asked for the stimulus. Rossi supports repealing the Patient Protection and Affordable Care Act and the Dodd-Frank Wall Street Reform and Consumer Protection Act. He also criticized Murray for her support for earmarks. In response, Murray said, "You bet that seniority and leadership has a big thing to do with it, but the other part of it is, I get up every day and I work hard and I believe in this and I am going to continue fighting for the community I represent." The National Rifle Association spent $414,100 supporting Rossi and opposing Murray in the 2010 senatorial contest.

Debates

Rossi offered six debates, five of which would be in-state and one nationally. Murray agreed to two debates, and only two debates were held.

Fundraising

Predictions

Polling

Aggregate polls

Results

Murray defeated Rossi by about 114,000 votes. King County, the home of Seattle, likely gave Murray a victory.

Counties that flipped from Democratic to Republican

By congressional district

Murray won 5 of 9 congressional districts.