WASHINGTON — Sen. Barack Obama acknowledged Sunday that he had failed to understand how much violence would decrease this year in Iraq, but he contended that President Bush and Sen. John McCain, the Republicans’ presumptive presidential candidate, had made the same mistake.

Meanwhile, McCain insisted in an interview on ABC’s “This Week” that he had not shifted his support of an American exit in 2010, despite comments he made Friday that the 16-month withdrawal plan espoused by Iraq’s prime minister “is a pretty good timetable.”

Addressing what has become one of his most difficult campaign issues, Obama said that the violence “has gone down more than any of us have anticipated, including President Bush and John McCain.”

But the presumed Democratic presidential nominee, appearing on NBC’s “Meet the Press,” contended that the decline was brought about not just by the U.S. troop increase, but also by a combination of factors, including Iraqi Sunnis’ decision to turn against al-Qaida.

Oil money flows to McCain after his drilling reversal

Campaign contributions from oil industry executives to McCain rose dramatically in the last half of June, after he made a high-profile split with environmentalists and reversed his opposition to the federal ban on offshore drilling.

Oil and gas industry executives and employees donated $1.1 million to McCain last month — three-quarters of which came after his June 16 speech calling for an end to the ban — compared with $116,000 in March, $283,000 in April and $208,000 in May.

McCain said the policy reversal came as a response to rising voter anger over soaring energy prices. Opening vast stretches of the country’s coastline to oil exploration would help America eliminate its dependence on foreign oil, he said.

“The timing was significant,” said David Donnelly, the national campaigns director of the Public Cam­paign Action Fund, a non­partisan campaign fi­nance re­form group that analyzed McCain’s oil industry contributions. “This is a case study of how a candidate can change a policy position in the interest of raising money.”

Brian Rogers, a McCain campaign spokesman, said he considers any suggestion that McCain weighed fundraising into his calculation on drilling policy “completely absurd.” Rogers noted that oil and gas money in June still accounted for a very small fraction of the $48 million raised by the campaign and by the Republican National Committee through its Victory Fund.

Oil and gas executives have not traditionally been a major source of campaign money for McCain. A breakdown of giving by the Center for Responsive Politics shows the industry falls 12th on a list of top donors, well behind securities firms, lawyers, banks and real estate and health professionals.

Anti-affirmative action initiative gets McCain nod

McCain said Sunday that he supports a proposed ballot initiative in his home state that would prohibit affirmative action policies from state and local governments. A decade ago, he called a similar effort “divisive.”

McCain was asked whether he supported an effort to get a referendum on the ballot in Arizona that would “do away with affirmative action.”

“Yes, I do,” said McCain in an interview broadcast Sunday on ABC’s “This Week.”

The Republi­can senator quickly added that he had not seen the details of the proposal. “But I’ve always opposed quotas.”

Over the years, McCain has consistently voiced his opposition to hiring quotas based on race. He has supported affirmative action in limited cases. For example, he voted to maintain a program that encourages the awarding of 10 percent of spending on highway construction to women and minorities.

In 1998, a resolution in the Arizona Legislature would have asked voters to eliminate most preferences based on race, gender, color or ethnic origin. McCain warned against using ballot proposals to outlaw quotas or racial preferences.

“Rather than engage in divisive ballot initiatives, we must have a dialogue and cooperation and mutual efforts together to provide for every child in America to fulfill their expectations,” McCain said.