Less than a week before the Republican primary election, anonymous callers phoned some of the Republican candidates running against Souder, with allegations that he was regularly meeting a girlfriend for romantic trysts in state parks. One alleged that he and a staffer went together late at night to the remote and heavily-forested Robinson Lake boat launch in Whitley County. But the opponents questioned the reliability of the information, and did not make a public issue of the claims.
According to the Post, the affair began after the staffer, Tracy Jackson, was hired to guest host for Souder on a Christian radio show in 2004.
So did something else happen that would compel Souder to come forward now? The Post reports that Souder was confronted about the rumors by his chief of staff last week.
But also of interest is this statement -- a departure from Souder's prepared remarks -- from his press conference today:
"I'm resigning rather than put my family thorough a painful drawn out process, of which any legal question would have been clearly resolved and I would have been exonerated."
It's still not clear what he is referring to.
Michael Steel, a spokesman for John Boehner, tells TPMmuckraker that Souder spoke with the minority leader on Monday. Steel declined to comment on whether Souder raised issues beyond the affair, saying only: "Boehner has been perfectly clear that he will hold our Members to the highest ethical standards."
And remember, Fox has quoted unnamed Republican aides as saying that Souder's conduct would have landed him before the ethics committee.
So it's increasingly clear there's something more than a plain old affair here -- the question is what.
Late Update: Phil Bloom, spokesman for the Indiana Department of Natural Resources, which has jurisdiction over state parks, says in a statement:
"The DNR has received media inquiries today regarding U.S. Cong. Mark Souder. Typically, Division of Law Enforcement procedures would require a formal public records request for information on any enforcement action taken by an Indiana conservation officer. However, due to the number of calls, we did an electronic search of our law enforcement data base as a courtesy to the media. That search turned up no mention of Cong. Souder."