Sarah Palin and her husband, Todd, have endorsed Deb Fischer, providing the state Senator’s struggling bid to succeed retiring Sen. Ben Nelson (D) an adrenaline shot six days before the GOP primary.

“I am writing to you as both a fan of your strong, conservative principles and as a fellow female Republican,” Fischer wrote to Palin. “I have watched your career with respect as you take on tough issues, all while raising a family and serving your great state. Your career has inspired me and so many other female politicians who believe principles should be above politics.”

The Palins wrote back six days before the primary.

“We are happy to support you and have asked SarahPAC to send a financial contribution to your campaign,” they wrote. “Good luck next Tuesday — the Palins are in your corner.”

The endorsement is an enormous boost to what had previously been an also-ran campaign. Fischer has struggled mightily for both attention and campaign funds in a field of three. Her GOP opponents include state Attorney General Jon Bruning, widely considered the frontrunner, and state Treasurer Don Stenberg, who has benefited from the support of the likes of the Club for Growth and Sen. Jim DeMint (R-S.C.).

Stenberg’s coalition resembles Indiana Treasurer Richard Mourdock’s backers in his Tuesday defeat of Sen. Dick Lugar in the state’s GOP primary.

On Tuesday, Stenberg picked up a high-profile endorsement as well, from Sen. Rand Paul (R-Ky.).

“Conservatives in the Senate need reinforcements; and that is why we need Don Stenberg to serve with us,” Paul said in a statement. “Don is the true conservative and will be a leader in Washington.”

The winner of the GOP primary will face presumptive Democratic nominee and former Sen. Bob Kerrey. Roll Call rates this race as Leans Republican.