By Mark Willen, Senior Political Editor June 26, 2009 How can there be any doubt? South Carolina Gov. Mark Sanford, R, has broken the law and violated his oath of office. He should resign today. Not because of his infidelity. Not because of his hypocrisy. Not because of his excessive desire for privacy. Those are all matters for South Carolina voters to judge. But he spent state funds on his affair, and he had to know that is grounds for impeachment. He's trying desperately to hang on, but instead he should resign and save the state the extra expense of kicking him out.Some will be appalled by his infidelity, but let's face it, it's a pretty common event. As Gail Collins notes with her usual wit, if we want to avoid that, we have to stop electing middle-aged heterosexual men to high office (although plenty of gay men have crossed the line as well). And once you get lenient in allowing sexual indiscretions, you have to expect a certain amount of lying to cover it up. The hypocrisy is something liberals will make a big deal about, but hypocrisy on morality is no worse that hypocrisy on any issue -- say railing against unnecessary spending and then securing an earmark for something silly in your district. If we try to eliminate every politician guilty of such inconsistency, there won't be anyone left. But Sanford clearly crossed the line when he used taxpayer money to pay for a tryst with his Argentine mistress. Sanford admits he took time away from a trade mission to Argentina last year for his dilly dallying. He now acknowledges that was a mistake and says he'll repay the state the $12,000 it cost taxpayers. A mistake? Hardly. He knew it was theft when he did it and he should be punished. Advertisement And someone should question the $12,000 figure. The trip was originally planned for Brazil, but Sanford added the Argentine stop, even though the U.S. government saw little hope of expanding trade with Buenos Aires, which has been a financial pariah since it defaulted on its debt. If the entire stop was a ruse, the bill should be a whole lot higher. This is where the hypocrisy thing really gets delicious. Sanford made his reputation on fiscal frugality, even saving state money by making staffers write on both sides of Post-it notes -- to say nothing of his fight to refuse stimulus money for the unemployed while he was spending thousands for what he calls the "sparking" thing. He also used a state vehicle, with the GPS tracking device disabled, to drive to the Atlanta airport for his latest trip. Come on. This is fraud and theft. The guy's got to go.