It's as if politicians never learn. The old Watergate adage, "It's not the crime; it's the cover-up" became a cliche precisely because of its political salience. And yet, even now, leading Republican presidential candidates seem oblivious to the lesson.

In Rudy Giuliani's case, the Shag Fund scandal continues to dog the former mayor, not just because he used taxpayer money to subsidize his adultery, but also because he tried to hide the expenditures and continues to lie about what transpired. The "crime" is embarrassing, but the "cover-up" keeps the story alive.

In Mike Huckabee's case, the Wayne Dumond controversy is part of the same phenomenon. Huckabee, for apparently political reasons, pushed for the release of a convicted rapist, who had become a right-wing cause celebre. Free, Dumond went on to rape and kill again.

Given what transpired, Huckabee had one viable option: acknowledge the truth, express regret, and promise voters that he learned from the mistake. Instead, Huckabee not only pushed to let a violent criminal out of jail for political reasons, he's lying about it now. Huckabee's "crime" was a tragedy, but it's the "cover-up" that will likely undermine his presidential campaign.

First, Huckabee insisted that he had no way of knowing that Dumond was still dangerous when he pushed for his freedom. That wasn't true. Second, Huckabee insisted that he did not pressure Arkansas' parole board to release Dumond. As it turns out, that's demonstrably false, too.

Huckabee had a chance to tell the truth and get this painful ordeal behind him. Unfortunately for him, he made the wrong call. The cover-up may not be worse than the crime, but the political impact is likely to be far more damaging.