The campaigns of Senators Obama and McCain traded blows yesterday over reports that an adviser to Senator Obama’s vice presidential search, James Johnson, obtained loans from and had a close friendship with the leader of a company mired in the subprime mortgage crisis, Angelo Mozilo of Countrywide Financial Corp.

Early yesterday, the Republican National Committee put out two news releases attacking Mr. Johnson, citing a Wall Street Journal report that he took more than $7 million in loans from Countrywide under an informal program for “friends of Angelo.” The Republican salvos also cited a report in The New York Sun yesterday that Mr. Obama had railed against Mr. Mozilo on the campaign trail and that Mr. Johnson praised Mr. Mozilo’s planning to help his firm weather a downturn in the housing market.

In an interview yesterday with Fox News, Mr. McCain weighed in, suggesting that Mr. Johnson’s involvement was at odds with Mr. Obama’s claims to fighting against Washington insiders. “It suggests a bit of a contradiction talking about how his campaign is not going to be involved with people like that. Clearly, he is very much associated with that,” Mr. McCain said.

Talking points issued by Mr. Obama’s campaign, and posted on Time Magazine’s Web site, called the story “overblown and irrelevant.”

“This is an overblown story about what appear to be completely above-board transactions. The Wall Street Journal even admits they don’t have a story noting that it’s ‘impossible’ to know the factors that went into these arrangements,” the campaign said. Mr. Obama’s camp also took a swipe at one of Mr. McCain’s advisers, John Green, noting that he lobbied for a large subprime lender, Ameriquest.

“There is nothing ‘overblown and irrelevant’ about millions of Americans facing foreclosure and Barack Obama entrusting his most important decision as a presidential candidate to a man who has accepted millions in special loans from a subprime mortgage lender,” a spokesman for Mr. McCain, Tucker Bounds, replied. He also noted that earlier in the campaign a senior aide to Mr. Obama, David Axelrod, faulted an adviser to Senator Clinton, Mark Penn, for doing consulting work for Countrywide.

A lawyer for Mr. Johnson, Brian Brooks, did not return calls Sunday or yesterday seeking details about the loans. Officials at Countrywide also failed to respond to inquiries about whether the loans to Mr. Mozilo’s friends were the subject of any of the various investigations taking place into the firm.