Not if you pick your battles wisely. Florida in 2000 is an example of that. James Baker and Racicot were ferocious bulldogs in that battle -- they didn't give an inch.
In contrast, Thune in SD chose to concede to Johnson in 2002 even though there was lots of evidence of fraud, esp. on India reservations. Thune bowed out gracefully, lived to fight another day, and dethroned Daschle.
But if he had stood his ground and made his case, might he not have taken his rightful seat against Johnson? Then we would have had another Republican for two years to help our cause, especially on some of these judicial nominations. Then when the Daschle contest came up, we might have been able to run an equally strong candidate and still beaten Daschle in '04 (I think people were fed up with his obstructionist record, so he was ripe to fall), and have 56 seats in our control in this session.
My point is that forgoing too many challenges in the hopes of winning "another time" can actually cost you ground in the long term.
I've seen this Thune analogy posted often on these threads and I will say again for those who are tempted to draw the comparison between John Thune and Dino Rossi, there is none. Thune was running for the same post he wanted in '02 against Johnson. For him it was a true re-match for the same prize. Thune wanted to be in the Senate, Rossi does not.
Rossi ran for Governor to change things in his state. The Governor's position is the best one to do that from. He has indicated in no uncertain terms that he isn't interested in the US Senate. He probably could not win that contest anyway against Cantwell, who is a much more attractive candidate statewide than Gregoire. Rossi knows that even if he somehow managed to win the consolation prize of a Senate seat, there'd be little he could do to help turn around his state after 20 years of ruinous 'Rat control. Being one vote out of a hundred, dealing with arcane and far-removed national issues, a junior Senator from a state without much political influence in DC, would be like being buried for 6 years on the sidelines. My impression of Dino Rossi is that he's a doer, and wants to get his hands dirty making things happen. The US Senate tends to be a place for glory hounds and Presidential wannabees. I doubt if Rossi would want to be a part of that.