Cameron Frye says this is what happens when you go too long without sticking up for yourself.You know you’ve got a race on your hands when the incumbent finally starts shooting back at his challengers. Perhaps emboldened by his ABDC shout-out (who’d have thought a clip of Greg Nickels would run on a Mario Lopez-hosted show?), perhaps rattled by the latest poll numbers, or perhaps just sick and tired of taking tunnel shots from Mike McGinn, Greg Nickels took a few of his own at the bike-riding challenger.In a release yesterday, the Nickels campaign said it was clearing up “the distortions and half-truths about candidate Mike McGinn’s position on the Alaskan Way Viaduct.” McGinn, as you know, opposes the deep-bore tunnel, arguing that it will put Seattle taxpayers on the hook for an environmentally unsound boondoggle. Yesterday, he sent out a release calling out Nickels and Joe Mallahan, asking how they plan to pay for the tunnel in light of Seattle’s reportedly bleak budget situation.I know you are but what am I, replies Nickels. He argues that, because the state has agreed on the tunnel and could pull its money, and because the $930 million is for a seawall replacement that must happen anyway, a McGinn mayorship would mean higher taxes for Seattleites, as we’d have to pay for our waterfront solution all by ourselves. To that end, his campaign will be robo-calling voters to make his case, and he says we should look at his new, slightly altered TV ad, in which Barack Obama gets the longest speaking part. Unfortunately for Nickels, an August all-mail primary and its oldie voters is a far cry from November ’08, with Barack-star exciting the young masses and transit on the ballot.