The congressman is the first U.S. House incumbent to be ousted this spring primary season amid widespread anti-incumbent sentiment. The same unrest helped end the 17-year career of Utah Republican Sen. Bob Bennett, who lost a GOP convention on Saturday.
State Sen. Michael Oliverio carried 56 percent of the vote to Mollohan's 44 percent Tuesday night after an aggressive campaign that questioned the incumbent's ethics and support for issues including federal health care reform.
"We announced our campaign 100 days ago, and in 100 days' time our country has fallen one-third of a trillion dollars further into debt," Oliverio said. "We have to get the country's financial house in order, and that's what we're committed to doing."