"I greatly appreciate the support and encouragement of the many Nebraskans who have urged me to consider a campaign for the United States Senate. After considerable reflection, I have decided not to run for the Senate,” he said in a statement.

Fortenberry faced criticism from conservativs, with the Senate Conservative Fund emailing its supporters to "beware of Fortenberry" and to oppose his potential candidacy.

His decision further diminishes the slate of potential contenders for retiring Sen. Mike JohannsMichael (Mike) Owen JohannsMeet the Democratic sleeper candidate gunning for Senate in Nebraska Farmers, tax incentives can ease the pain of a smaller farm bill Lobbying World MORE' (R-Neb.) seat. Gov. Dave Heineman said this weekend that he won't run for the seat either.

But Republicans aren't concerned they'll manage to hold the seat, as Nebraska's Republican lean and the thin Democratic bench in the state leave them a clear path to victory.

Two contenders who lost in 2012 — State Treasurer Don Stenberg  and state Attorney General Jon Bruning — could run. Former state Treasurer Shane Osborn is considering it, and Reps. Adrian Smith and Lee Terry have not yet ruled it out.