The top campaign strategist for Senate Republicans hopes the GOP’s string of losses in special House elections this year will provide a jolt of energy to his colleagues and burn away any complacency among the troops.

On Wednesday, National Republican Senatorial Committee Chairman John Ensign (Nev.) repeated his warning that Republicans up for re-election this year cannot afford to take their contests lightly.

Despite months of warnings from Ensign and others of the challenges of the 2008 cycle, many Senate Republicans have been slow to raise funds, set up campaign operations or take other steps that would indicate a sense of urgency.

While some Members up for re-election, such as Minority Leader Mitch McConnell (R-Ky.) and Senate Republican Conference Vice Chairman John Cornyn (Texas), have been aggressively campaigning and fundraising, others, like Sen. John Sununu (R-N.H.), have been slower to put together their campaign operations.

But Republicans hope Tuesday’s defeat of Southaven, Miss., Mayor Greg Davis (R) to Democrat Travis Childers in a special election for a vacant House seat has brought renewed urgency to their Conference.

“It’s getting peoples’ attention, that’s for sure,” Cornyn said Tuesday.

Ensign, who has become increasingly frustrated with his colleagues’ lack of urgency in the runup to the November elections, said during a meeting Wednesday with his GOP colleagues that Republicans face an increasingly difficult year and that they should write off the string of recent House losses as unrelated to the party’s prospects in the Senate.

“That’s what I told them. … If you are a Republican do not take anything lightly,” he said.

Although some Republicans sought to downplay the significance of the string of losses, particularly in terms of what they portend for the Senate, Ensign rejected that kind of thinking. While “any one of these races you could explain away on extenuating circumstances,” they should be viewed as a sign of how difficult it will be for both Republican incumbents and challengers to win this year, Ensign said.

Ensign also said that Tuesday’s results demonstrate that no matter how solidly Republican an area or state is, it is imprudent to take that for granted. Races “in Texas, in Kansas, in Mississippi, any one of these races that should be safe” no longer are, Ensign warned.

“There’s no denying the fact that this is going to be a challenging election year,” Cornyn said. The Texan is one of a handful of incumbents who has been aggressively raising funds despite relatively rosy electoral prospects. Like McConnell — who leads his GOP colleagues in cash taken in this year — Cornyn has been campaigning for months. He has raised a total of $13.4 million this cycle and has $8.6 million on hand, ranking him second behind McConnell, according to aides.

Cornyn said he believes that the message from this year’s special elections is sinking in and that he hopes the lessons will not be lost on his party. “Let’s hope we learn whatever lessons there are to be had from this and move on,” Cornyn said.

Senate Republican Steering Committee Chairman Jim DeMint (S.C.) agreed, saying that while Tuesday’s results are unlikely to be seen as a harbinger for this fall’s Senate election in Mississippi, the string of losses should be a wake-up call to other Republicans. He also said the defeats have spurred renewed talk within conservative circles of the need for the party to bring its policies back into line with the conservative principles they say helped sweep the GOP to power in 1994. “These three or four losses have caused numerous discussions about the need to let Americans to know what we stand for and to put some real action behind those words,” DeMint said, adding that “we’ve lost our moorings to these principles … I’m hoping it will be a wake-up call.”

Ensign said GOP candidates need to “run hard and do everything you need to do to get elected. It needs to definitely be a wake-up call that any of these [candidates] that thought they could be complacent, they better not be,” Ensign said.