Texas Gov. Rick Perry is a successful politician in Texas. But he’s never been a great one.

Michael Barone points out: “Rick Perry has been elected governor of Texas three times, beating Democrat Tony Sanchez 58%-40% in 2002, winning a four-way race against Democrat Chris Bell and Independents Carole Keeton Strayhorn (who had been elected to statewide office as a Republican) and Kinky Friedman by a 39%-30%-18%-12% in 2007 and beating Democrat Bill White 55%-42% in 2010. That 55% is the same as John McCain’s percentage in Texas in 2008 and Senator John Cornyn’s percentages in 2002 and 2008. It is lower than the 61% to 67% Senator Kay Bailey Hutchison won in four elections from 1993 to 2006 and below the 59% to 64% that Republicans facing Democrats for other statewide offices won in 2010.” Barone points out that he had good opponents, but this suggests he was not an intimidating force that cleared the field.

However, these wins and the bells and whistles (and mansions) that go along with being a governor are heady stuff. It gives one the impression that critics don’t need to be taken seriously. It gives a sense of invincibility (and who couldn’t be under a spell with all those Texas rangers accompanying you?) And it is in that regard that Perry has wounded himself.

The Wall Street Journal’s editorial board provides a good example. Perry’s position on in-state tuition for illegal immigrants is defensible, but he didn’t bother to come up with a well-thought out excuse. Instead he ridiculed his critics:

Mr. Perry didn’t help himself by calling his critics on this issue heartless, and he could do a better job of explaining the program’s rationale. Lower in-state tuition rates at public colleges and universities aren’t akin to welfare for the indigent; they’re not means-tested. They’re a discount for residency. The same logic applies to hunting or fishing licenses.

Immigration status aside, state residents are thought to be deserving of a subsidy because they pay sales taxes, property taxes and other fees to support state institutions that nonstate residents don’t pay. Especially in a state like Texas that has no income tax, illegal aliens are more likely to bear a larger share of the tax burden than their counterparts in most other states.

But Perry didn’t provide that sort of thoughtful response. He’s convinced he’s right. End of story. (Notice the resort to cloying liberal-like compassion on both this and the HPV vaccine. He hates cancer you see; his opponents don’t, I suppose.) It doesn’t suggest he understands that a politician must persuade and not simply mow down his critics.

Then there is Perry’s latest attempt to criticize Mitt Romney. His incoherent attack on Romney in the last debate set of waves of panic in the GOP electorate. (By gosh what if he had done that against Obama?!) But he then doubled down with an ad so obviously dishonest on Romney’s position on Race to the Top that there weren’t enough Pinnochios to go around. The Post’s Glenn Kessler can barely keep up.

Glenn also found that another Perry ad aimed at Romney that misstates a change between the hard copy and paperback copy of Romney’s book. (“Perry could have made a reasoned attack on the type of health-care reform that Romney supported, but instead he chose to manufacture a phony issue. Romney has long said he did not view his plan as a model for the nation, and he has not wavered on that stance.”)

The difference here is not that the Perry camp is any less honest than other campaigns. It is that his staff seems not to appreciate that you can’t say just anything and get away with it in a presidential race (unless you’re a Democrat in the general election). You can spin, but you can’t flat out lie. You can stretch but you can’t blow your credibility with the media covering you or with the voters. Sooner or later they stop listening and believing much of anything you have to say.

This is an especially fatal flaw for a self-described conviction politician. He’s supposed to be a truth-teller and antidote to professional politicians. But what if he is simply a professional politician less skilled than his competitors? Well, we’re finding out.