ENSIGN’S EVOLVING MOTIVATION…. So, why did Sen. John Ensign (R-Nev.) publicly acknowledge his extra-marital affair with an aide? It’s a humiliating revelation, which has already cost Ensign his leadership position among Senate Republicans, but it’s still a little unclear what Ensign was hoping to achieve.

The original line was that Ensign believed his mistress’ husband, another former aide to the senator, was going to blackmail him. Today, we get another possible explanation — the husband sent a letter to Fox News’ Megyn Kelly, giving her the scoop on the story.

In a letter dated five days before Sen. John Ensign’s public confession of an extramarital affair, Doug Hampton pleaded to a national Fox News anchorwoman for help in exposing the senator’s “heinous conduct and pursuit” of Hampton’s wife.

Hours before the Sun obtained an unsigned copy of the letter, Ensign’s spokesman said the senator disclosed the affair with Cynthia Hampton because her husband had approached “a major television news channel before Tuesday,” the day Ensign admitted the affair. “We learned of this fact before the news conference,” the spokesman noted in an e-mail.

Doug Hampton’s letter to Fox News’ Kelly is a little odd, but it explains Ensign’s “relentless pursuit of my wife,” which “ruined our lives and careers and left my family in shambles.” He offered to present a “paper trail, phone records and personal witnesses” to bolster his accusation against Ensign, and urged Kelly to “please help” him.

He added that he “could have sought the most liberal, Republican hating media to expose this story, but there are people’s lives at stake and justice is about proper process as well as outcome. Senator Ensign has no business serving in the US Senate anymore!”

The Politico added that this letter “sheds new light on why Ensign decided to make the announcement Tuesday.” Well, maybe.

Doug Hampton wrote a long, strange letter to a pseudo-journalist who works at a network committed to helping conservative Republican officeholders and candidates. Are we to assume John Ensign’s Senate office heard about the letter to Fox News and leapt into action, genuinely worried that Megyn Kelly would humiliate the senator by launching an exclusive Fox News investigation into this? Isn’t it far more likely that Kelly would have ignored the letter?

Maybe Ensign and his aides figured that Hampton would, sooner or later, find someone in the “liberal, Republican-hating media” to report on this, and it was better to take control of the story before that happened. But I find it hard to imagine the senator and his team were seriously worried about a hard-hitting Megyn Kelly expose against a fellow Republican.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.