Ask any zealot the reason for Minnesota's proposed constitutional amendment requring that voting be allowed only by  bearers of government-issued photo ID cards, and they will invariably say: It's to prevent fraud.

They must mean that it would prevent one voter from impersonating another at the polls. That's the only kind of fraud a photo ID would prevent. It's an almost unheard-of crime in Minnesota.

But as Washington Post columnist Eugene Robinson reported, a legislator in Pennsylvania was willing to say more last month before a friendly Rebublican audience. The Keystone State's new photo ID law would deliver its electoral votes for Republican Mitt Romney this year, assured state Rep. Mike Turzai.

Pennsylvania has been nearly as reliably blue as Minnesota has been in presidential politics. For Turzai to claim that photo ID will switch Pennsylvania from Democratic blue to Republican red, he must believe either that voter impersonation is rampant and occurs only among Democratic voters, or that the impact of the photo ID requirement would go way beyond fraud prevention -- as the League of Women Voters, AARP, Lutheran Social Services and other opponents of Minnesota's proposed amendment have been saying all along.

Pennsylvania's equivalent of MnDOT recently issued some revealing stats: 9.2 percent of already registered Pennsylvania voters presently lack either a driver's license or an alternative state-issued photo ID card. In the highly Democratic city of Philadelphia, that percentage jumps to 18 percent. Here's hoping MnDOT generates similar numbers in Minnesota soon, to help voters understand who would be affected by a constitutional photo ID requirement -- and where they live.