White House officials on Sunday dismissed Republican attacks over three simmering scandals as a partisan witch hunt, hoping to put behind them President Obama's single worst week in office and to move Washington's attention back to his second-term agenda.

While Obama was delivering a commencement address at the historically black Morehouse College in Atlanta, his top surrogates fanned out across the Sunday morning talk shows to defuse claims that the administration has violated constitutional boundaries and to blame the controversies on partisan politics as usual.

"We've seen this playbook from the Republicans before," Dan Pfeiffer, a senior Obama adviser, said on NBC's "Meet the Press." "What they want to do when they're lacking a positive agenda is try to drag Washington into a swamp of partisan fishing expeditions, trumped-up hearings and false allegations. We're not going to let that happen."

The White House has been all but consumed by revelations that the Internal Revenue Service targeted conservative political opposition groups, the Justice Department was secretly monitoring journalists' phones and that administration officials had heavily edited public disclosures of a deadly terrorist attack in Benghazi, Libya, months before Obama's re-election.

Republicans, however, remained on the attack.

"There is a culture of intimidation throughout the administration. The IRS is just the most recent example," Senate Minority Leader Mitch McConnell, R-Ky., said on the NBC program. "What we're talking about here is an attitude that the government knows best; the nanny state is here to tell us all what to do. And if we start criticizing, you get targeted."

A CNN/ORC International poll released Sunday found the president's approval rating holding steady at 53 percent, but it also showed that most people support Republican claims that the trio of controversies warrant investigation. The public considers the IRS targeting, Justice Department monitoring and the handling of Benghazi all "very important to the nation," the poll showed.

The White House is furiously trying to divert attention from the trio of controversies and get back to the president's agenda. Obama on Thursday will speak to the National Defense University about his broken promise to close the Guantanamo Bay prison and the legal rationale behind his unparalleled use of drone strikes overseas.

However, the White House is still struggling to describe what officials knew of the three scandals and when they learned of them. Pfeiffer on Sunday insisted the White House first learned of the investigation into the IRS "a few weeks ago," even though senior Treasury officials were alerted about the activity last June.

And Bob Woodward, the Washington Post reporter who uncovered the Watergate scandal that led to President Richard Nixon's downfall, said there are parallels between the Nixon administration abuses of power and current allegations against Obama.

"This is not Watergate, but there are some people in this administration that have acted as if they want to be Nixonian, and that is a very big problem," Woodward said on "Meet the Press," citing the administration's efforts to downplay the role terrorists played in the attacks on the U.S. Consulate in Benghazi. "This is a business where you have to tell the truth and that did not happen here."