Fischer was the early favorite to win the seat in red-leaning Nebraska, where Mitt Romney has consistently held a double-digit lead over President Obama for the entirety of the election.

But Kerrey, a well-liked former Nebraska governor, posted a last-minute surge in the polls, narrowing Fischer's formerly substantial lead to single digits in one poll released in the final weeks of the election.

His sudden strength prompted the entry of outside groups from both sides, and a high-profile endorsement from former Nebraska Republican Sen. Chuck HagelCharles (Chuck) Timothy HagelIntel chief: Federal debt poses 'dire threat' to national security Hagel: Trump is 'an embarrassment' Tax cut complete, hawks push for military increase MORE.

But the late support wasn't enough to help Kerrey overcome the perception, cultivated early on by Fischer, that Kerrey was a liberal outsider who had lost touch with Nebraskans during a decade spent in New York.