LACONIA, N.H. — His credibility under attack, Republican presidential hopeful Mitt Romney insisted Friday he had "no role whatsoever in the management" of a private-equity firm after early 1999, and demanded President Obama apologize for campaign aides who persist in alleging otherwise.

"This is simply beneath the dignity of the presidency of the United States," Romney said in an ABC interview, one of several he granted to network and cable stations in hopes of extinguishing the controversy.

Under pressure from Democrats and even some Republicans to release tax returns going back several years, Romney said he'll only release to the public one more tax return — and not until his accountants complete it.

Romney told CNN he's complied with the law by filing a financial-disclosure statement.

He said that after he left Bain Capital he retained ownership "until we were able to negotiate a departure" from the company he had founded. "I had no role whatsoever in the management of Bain Capital after February of 1999," he said, adding that officials at the company and independent fact checkers had said the same thing.

He also said, "I was an owner and being a shareholder doesn't mean you're running the business." He couldn't recall attending any Bain management meetings after he moved to Salt Lake City to oversee planning for the 2002 Winter Olympics.

The precise role Romney played at the firm between 1999 and 2001 is important not only because critics have raised questions about his truthfulness, but also because Bain was sending jobs overseas during that period.

That, in turn, goes to the core issue of the race for the White House in dreary economic times: Romney's claim that as a former businessman, he has the ability to create jobs and finally pull the country out of a downturn that has lingered throughout Obama's term.

The Obama campaign has criticized Romney as running a firm that pioneered job outsourcing.

Some Securities and Exchange Commission documents have surfaced suggesting Romney played an active role in the Boston-based company through 2002. The filings with the SEC place Romney in charge of Bain Capital from 1999 to 2001, the period in which it outsourced jobs and ran companies that fell into bankruptcy.

Romney was particularly harsh when asked about a claim by Obama deputy campaign manager Stephanie Cutter suggesting he might be guilty of a felony for misrepresenting his position at Bain to the SEC.

"Is this the level that the Obama campaign is willing to stoop to?" he responded on CNN. "Is this up to the standards expected of the presidency of the United States?"

Separately, Bain Capital issued a statement saying that Romney "remained the sole stockholder for a time while formal ownership was being documented and transferred to the group of partners who took over management of the firm in 1999."

Obama spends big

on TV spots

WASHINGTON — President Obama's campaign has spent nearly $100 million on television commercials in selected battleground states so far, unleashing a sustained early barrage designed to create lasting, negative impressions of Republican Mitt Romney before he and his allies ramp up for the fall.

In a reflection of campaign strategy, more than one-fifth of the president's ad spending has been in Ohio, a state that's a must-win for Romney more so than for Obama.

Florida ranks second and Virginia third, according to organizations that track media spending and other sources.

About three-quarters of the president's advertising has been critical of Romney as Obama struggles to turn the election into a choice between him and his rival, rather than a referendum on his own handling of the weak economy.

Obama's television-ad spending dwarfs the Romney campaign's so far by a margin of 4-1 or more. It is at rough parity with the Republican challenger and several outside GOP-led organizations combined. They appear positioned to outspend the president and his allies this fall, perhaps heavily.

The latest attack ad, which began airing Friday, accuses the Republican of favoring a 25 percent tax cut for millionaires, tax breaks for oil companies and corporations that move jobs overseas and a tax increase for working families. By contrast, it says, the president wants "the wealthy to pay a little more so the middle class pays less."

Democrats and even some Republicans agree the effort to cast Romney as an unfit steward for the economy shows signs of making some headway. Yet GOP strategists hasten to add that the former Massachusetts governor has ample time to counter, particularly with recent signs of a struggling economy and the fall campaign yet to begin.

Wanted to buy:

security barriers

CHARLOTTE, N.C. — Two miles of concrete barriers. More than five miles of 9-foot "anti-scale" steel fence.

Nearly eight miles of lightweight metal barriers and portable vehicle barriers designed to withstand the impact of a 15,000-pound car at 50 mph.

These are some of items the Secret Service is seeking to protect the Democratic National Convention (DNC) in Charlotte, N.C., according to a federal government contract request released this week.

The Secret Service's proposal lists four Charlotte sites that will be secured for the convention, to run Sept. 4-7.

Three of the sites are uptown: Time Warner Cable Arena, which will host the first two days of the DNC; Bank of America Stadium, the site of President Obama's expected acceptance speech; and the Charlotte Convention Center, which will host the media.

The fourth site slated for concrete barriers and anti-scale fencing is an empty warehouse near Charlotte Douglas International Airport. The Secret Service request doesn't say who will use the building.

The federal government hasn't yet released details on the security perimeter for the DNC. But the requests for fencing and barriers suggest that areas around convention sites will be heavily fortified.