National Republican Senatorial Committee Chairman John Ensign (Nev.) on Tuesday conceded his party would suffer significant losses in the Senate this election, but said there was little he or national Republicans could have done to alter the outcome.

“Obviously, we expected this kind of night,” Ensign said, adding that the “bottom line is that Democrats are going to have some big numbers in the Senate.”

With at least five — and as many as eight — Republican seats changing over to the Democratic Party in Tuesday’s balloting, Ensign defended his efforts to guide the NRSC this cycle. He argued that a tough political map and an unwillingness of several leading Republicans to challenge Democratic Senate incumbents made it impossible for him to achieve victory in 2008.

“We just caught a very, very, tough cycle. I think this was a tougher cycle even than [post] Watergate,” he said.

Ensign blamed a variety of issues including President Bush’s low standing in public opinion polls and the burgeoning economic crisis.

“We got blamed” for the economic collapse, Ensign said. “The vast majority of people blamed us for the economic crisis.”

Ensign said that in the past several weeks he and top staff had already begun a review of the 2008 efforts and determined that GOP Senate recruitment this cycle, while successful in some heavily Republican areas like Idaho, was lacking overall.

Specifically, Ensign lamented the decision by top prospects such as Rep. Denny Rehberg (R-Mont.) to seek re-election to the House instead of challenging Sen. Max Baucus (D-Mont.). “I don’t know what I could have done differently. I offered the world,” Ensign said.

Because the GOP couldn’t convince candidates like Rehberg to run, the NRSC had trouble knocking off any sitting Democratic Senators. Had he been successful, Ensign said, “Democrats would have had to play defense.”