If you turned on Fox News this weekend, you couldn’t miss coverage of the admission Friday by former Democratic presidential candidate John Edwards that he had an extramarital affair on the campaign trail in 2006 while his wife was stricken with cancer.

Flip through the channels and you heard this talking head and that talking head saying how his political career is over.

And they are right. It is.

But there remains one question: Is what he did worse than what presumed Republican presidential nominee Sen. John McCain did?

McCain has admitted to several affairs during his first marriage — to a woman who had remained loyal to him during his years in captivity in Vietnam.

Edwards had one instance of adulterous behavior. McCain had years of adulterous behavior. He eventually left his wife for a younger woman.

We’re not saying what Edwards did was right. It was not. And the fact that he was in the national limelight at the time of the affair — when so many Americans were reaching out to his suffering family — makes the affair seem like a lie to the American people. But we nevertheless find it difficult to skewer one politician over adultery without being “fair and balanced” to another politician who is still in the running for the highest office in the land.

If faithfulness in marriage has become a values test for political office and especially the presidency, then it isn’t hard to compare Sen. McCain to Sen. Barack Obama and decide who is the adulterer.