WASHINGTON » President Barack Obama finds himself under fire on two disparate fronts these days, both for the botched rollout of his signature health care program and for the secret spying on allied heads of state. In both instances, his explanation roughly boils down to this: I didn’t know.

As a practical matter, no president can be aware of everything going on in the sprawling government he theoretically manages. But as a matter of politics, Obama’s plea of ignorance may do less to deflect blame than to prompt new questions about just how in charge he really is.

In recent days, the president’s health and human services secretary said that despite internal concerns and a failed test run Obama was not told about serious problems with the new program’s website until it launched this month. Other officials said the president was not aware that the National Security Agency was tapping the phone of Chancellor Angela Merkel of Germany and other friendly leaders until this summer, although intelligence officials said Tuesday that others in the White House had known.

Opposition lawmakers and pundits have seized on the White House explanations to accuse Obama of being a "bystander president," as the Republican National Committee put it. Even Some Democrats are scratching their heads at the seeming detachment from significant matters. MSNBC’s "Morning Joe" ran a montage of clips showing Obama or his aides disclaiming presidential knowledge of various issues as well as a graphic titled "Implausible Deniability."

"It seems to me there’s a pattern here — with any bad news coming out of the administration, the excuse is the president just didn’t know about it," said Rep. Adam Kinzinger, R-Ill.

"There’s a point at which the I-didn’t-know excuse really violates the idea of the buck stops here," he added. "We want to have a feeling that the president ultimately takes responsibility. The American people want to know they have a president who’s in control and in charge."

Democrats were less likely to blame the president but suggested that he was ill served if other officials did not keep him fully abreast. "If people really knew there were to be problems, I was a little surprised that people at the highest levels weren’t aware," Patrick Griffin, who was a top White House official under Bill Clinton, said of the health care program.

As for the NSA surveillance, Sen. Dianne Feinstein, D-Calif., who leads the Senate intelligence committee, put it sharply in a statement she released earlier this week. "It is my understanding that President Obama was not aware Chancellor Merkel’s communications were being collected since 2002," she said. "That is a big problem."

Aides dismissed suggestions that Obama did not pay enough attention in either of these areas. On the spying program, they said the president was deeply immersed in details of the nation’s surveillance practices but was focused on those areas that constituted the major threats to the United States. He had no reason to suspect that Merkel or other leaders of close allies were being tapped, nor did he think to grill anyone about it because that was not a high priority, they said.

On health care, aides said that Obama has been fixated on details of the law’s implementation and that advisers did not withhold information but were likewise surprised by the scope of the problems.

"From the moment the health care bill was signed into law the president was very focused on making sure it was implemented correctly," said Dan Pfeiffer, a senior White House adviser. "In just about every meeting, he pushed the team on whether the website was going to work. Unfortunately it did not, and he’s very frustrated."

Pfeiffer insisted that the president wants to hear what he needs to hear and would not accept advisers keeping negative information from him. "He’ll know if you don’t tell him the bad news he needs to hear, and that’s the quickest way to be on the outside looking in," Pfeiffer said.

The challenge for any president is keeping on top of a vast array of issues, any one of which could blow up at any given time. Harry S. Truman spoke for many of his successors when he said that "the pressures and complexities of the presidency have grown to a state where they are almost too much for one man to endure." And that was decades before metadata technology came along.

A famous question posed by Sen. Howard Baker in a far different context — what did the president know and when did he know it — has been a staple of political controversies in the 40 years since Watergate. Jimmy Carter was accused of being too immersed in details, including who would use the White House tennis courts, while Ronald Reagan was criticized for being too hands-off, particularly when he insisted that he did not know about details of the Iran-Contra operation.

Accusations that Obama is removed from the details of his programs are somewhat surprising given the reputation the president developed early in his administration for intense, consuming interest in the particulars. Before ordering more troops to Afghanistan, for instance, Obama conducted what amounted to an exhaustive three-month series of seminars on the region.

But on other issues, he has seemed uninvolved at significant junctures. He has said he learned from news reports about the Fast and Furious program, a botched federal investigation into gun smuggling that allowed weapons to fall into criminals’ hands.

His staff knew about an investigation into the targeting of conservative groups by the Internal Revenue Service, but did not tell him until it was becoming public. Likewise, aides said the president was unaware of a Justice Department decision to secretly obtain reporter phone logs in a leak case.

Still, those cases underscore the difficult choices in what to tell a president. Aides determined that it would be inappropriate, not to mention politically risky, for the president to have advance knowledge of the IRS investigation. A president, they said, should not be involved in such investigations or law enforcement cases because if he were it could politicize them.

John Tuck, who was a White House aide under Reagan, said he was not as bothered as other Republicans about Obama not knowing about the problems with the health care system in advance. "I would never put the finger on somebody saying he should have known or might have known," Tuck said. "What difference does it make if he knew or he didn’t know?"

But in any White House, he said, the typical pattern is to try to insulate the president from responsibility for bad news. "If you had a good story you brought it to the White House," he said. "If you had a bad story you put it out to the department that was responsible for it."