Curt Weldon and the Prevailing Political Winds

It was just yesterday that I noted that CQPolitics.com had downgraded Weldon's chances to Leans Democratic from No Clear Favorite. Well the pixels were barely dry on that post, when I read that Weldon has been downgraded again:

Pennsylvania Republican Rep. Curt Weldon — already facing a difficult re-election contest in the state’s politically competitive, if not slightly Democratic, 7th District — must now grapple with the political fallout from a federal investigation into whether he improperly steered federal contracts to a lobbying business that his daughter co-owns.
Though Weldon has strongly denied the allegations, which he attributes to political motivations, the flurry of negative publicity has prompted CQPolitics.com is changing its rating on the Pennsylvania 7 race to Leans Democratic from No Clear Favorite.

A week ago, Weldon was seen as being in a tight race with challenger Joe Sestak. Today, he's seen as sharply behind with little chance of catching up. How did that happen?
Stories involving cozy ties between lobbyist and GOP lawmakers have been circulating all year. The Mark Foley scandal has been less about his conduct (he promptly quit when the story broke), than it has about the GOP leadership's failure to act in response to his unsavory behavior.
Curt Weldon's story calls his supposed expertise, and the supposed GOP political advantage, in foreign policy sharply into question. It doesn't help that he has some rather esoteric views of foreign affairs, such as his conviction that degraded chemical munitions from before the first Gulf War represents confirmation of Iraqi WMDs. Given that he's being challenged by a retired admiral, Weldon no longer enjoys the advantage of seeming stronger on national security.
Investigations into questionable lobbying makes for good headlines. Toss in a Russian energy tycoon and a Serbian businessman with ties to Slobodan Milosevic, and you've got a story that writes itself, as in this Washington Post piece:

Officials at the U.S. Embassy in Belgrade were surprised three years ago to be invited to a luncheon in honor of visiting Rep. Curt Weldon (R-Pa.), hosted by Bogoljub Karic, a wealthy Serbian businessman who had been barred from visiting or trading with the United States because of his close ties to former Yugoslav leader Slobodan Milosevic.
Weldon "was visiting solely because of Karic," whom he was trying to get off the U.S. blacklist, a former senior embassy official familiar with the visit concluded. "It seemed odd" at the time, because Karic had no obvious tie to Weldon's district outside Philadelphia, and Weldon should have known the embassy was shunning contacts with him, the official said.
What the embassy apparently did not know is that the Karic family that year signed a contract with Weldon's daughter, Karen, and a business partner that called for monthly payments of $20,000 for "management, government and public relations," according to a copy of the March 2003 contract. In all, the family paid Karen Weldon's firm $133,858 that year for efforts she undertook to set up a foundation for it.

So what does Weldon's sudden fall tell us about the national political winds? Usually stories about corruption require time to sink in, but with tales of Republican corruption saturating the media, voters seem disinclined to give GOP candidates the benefit of the doubt.