Democrat Suzanne Bonamici has been elected to replace former Congressman David Wu in Oregon's First District.
The election comes more than a year after the first public sign of trouble for a congressman who would eventually resign in a sex scandal.
Bonamici was the favorite in a district where Democrats outnumber Republicans and where President Barack Obama enjoyed significant support in 2008. She defeated Republican Rob Cornilles, the owner of a consulting business who said he was best qualified to create jobs.
Bonamici is a lawyer and a former state senator. She was helped to victory by a barrage of ads from national Democrats and their allies, who spent more than $1 million attacking her rival's business record. Republicans spent far less to boost Cornilles.
Former Rep. David Wu resigned from Congress in August after a newspaper reported that the 18-year-old daughter of a campaign donor accused the seven-term Democrat of making an unwanted sexual advance at a Thanksgiving dinner. His resignation capped months of reports about Wu's bizarre behavior during the 2008 and 2010 campaigns that led several staff members to quit.
The Associated Press contributed to this report.
On the Web