The time to be active is now, and the reason is the same as it always was: those who are more willing to have babies killed must not be given the power to do so.
Notice that I phrase that in the negative. Elections are often not about getting a satisfactory person in office as much as they are about keeping a worse person out of office. Elections are exercises of power and deal in the categories of "bad" and "worse"; "good" and "better," rather than "bad" versus "perfect." If we go into elections hoping to find perfect candidates, we will constantly be disappointed. But if we go into elections determined to improve things as much as possible — recognizing the limits of what that means, but also recognizing its significance — we will be energized.
Some people may wonder what the pro-life candidates they elected have done, or may feel they have not done enough. Important progress has been made, but far more is required, and we always have to keep the pressure on those we have elected. But if you prevent someone from falling off a cliff, you have already achieved something quite significant.
This raises a point I've been meaning to make for a while. Many pro-lifers are ready to desert the Republican Party because they see the GOP as unwillingly to take any meaningful action to limit abortion. (I would disagree with this: Bush has done quite a bit as President to move the executive branch in a pro-life direction.) Those who argue this, while having a point, fail to overlook the consequences of allowing the other side into power: if the status quo is bad, their vision of abortion law is much worse. Given the choice between the current status quo, and where the Democrats would take us, I'll choose the status quo every time.