Crapo, a Harvard University-trained lawyer, was an Idaho U.S. representative before switching to the Senate a dozen years ago.
Crapo banked more than $4.3 million in campaign donations, while Sullivan struggled to gain much traction after raising only about $70,000.
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Crapo is a member of the Senate Banking, Housing, and Urban Development Committee and voted against President Obama's health care overhaul, financial industry reforms and the 2009 federal stimulus.