As Joe Biden gets set for his big moment in Denver tonight, there's renewed scrutiny on the activities of his lobbyist son.

On Sunday, the Washington Post reported that Hunter Biden -- along with Joe Biden's brother, James -- is being accused in one lawsuit of defrauding a former business partner, and in a separate lawsuit of defrauding an investor in a hedge fund deal. The facts of the cases remain unclear, but the plaintiff in one of the suits, Anthony Lotito Jr., alleges that he entered into a deal with Hunter and James to create a hedge-fund group, Paradigm Companies LLC, before the Bidens crafted another deal to create a "secret company" designed to buy out Lotito's shares. The suit also claims that Hunter entered into the original deal as a way to get out of the lobbying business, thanks to concerns about the impact of his lobbying activities on his father's expected presidential run. The Bidens allege in response that Lotito defrauded them, according to the Post, by "misrepresenting his experience in the hedge fund industry and recommending that they hire a lawyer with felony convictions."

That same day, the New York Times had its own angle on Hunter's lobbying activities. It reported that, while Sen. Biden, a longtime ally of the credit-card industry, was working in support of the 2005 bankruptcy bill, which made it harder for consumers to file for bankruptcy, Hunter had a consulting agreement -- which may have been worth $100,000 a year -- with financial-services giant MBNA, one of the bill's biggest backers.

The Times adds this interesting detail:

Campaign officials acknowledged that the connection between the Bidens and MBNA, the enormous financial services company then based in their home state of Delaware, was one of the most sensitive issues they examined while vetting the senator for a spot on the ticket.

And now today, the Post uncovers a link between Hunter Biden and Obama himself, reporting that the Illinois senator "sought more than $3.4 million in congressional earmarks for clients of the lobbyist son of his Democratic running mate, Sen. Joseph R. Biden Jr. of Delaware, records show." The Obama campaign said that Hunter Biden never met directly with Obama, and noted: "It's hardly surprising that a Senator from Illinois would fight for investments in Mercy Hospital, Thorek Hospital and St. Xavier University right in Illinois, or that he'd be joined in that effort by a Republican colleague, Representative Judy Biggert."

Whether this stream of reports will create a lasting problem for the Democratic ticket -- particularly given Sen. Biden's own record of close ties to Washington lobbyists, particularly for the banking industry -- or whether they'll get lost in the ever-churning mill of campaign news, remains to be seen. But they certainly bear keeping an eye on.