The attacks from presumptive Republican nominee Mitt Romney on intelligence leaks put Obama campaign officials on the defensive Wednesday, as Republicans stepped up attempts to chip away at the president’s credibility on national security.

Obama senior campaign adviser David Axelrod was grilled on the leaks during an interview on MSNBC’s “Morning Joe,” where he shifted from his previous position.

“I can tell you that the president of the United States did not leak classified information, as Mitt Romney suggested yesterday, and he didn’t authorize the leak of information, as Mitt Romney suggested yesterday,” Axelrod said.

Axelrod previously denied that the leaks had originated with anyone at the White House.

“There were obvious leaks, but they weren’t from the White House,” he said in an interview in June.

The shift suggests a growing problem for the White House and Obama in the wake of comments from Sen. Dianne FeinsteinDianne Emiel FeinsteinDHS chief takes heat over Trump furor NSA spying program overcomes key Senate hurdle Democrats will need to explain if they shut government down over illegal immigration MORE (D-Calif.) this week that some of the leaks had to have originated in the White House. 

Feinstein backtracked from her comments Tuesday, but Romney used them in a speech on foreign policy to blame Obama for the disclosed intelligence secrets.

The Romney campaign continued to pile on Wednesday after Axelrod’s comments.

“Earlier this morning, Obama campaign adviser David Axelrod couldn’t deny what Sen. Dianne Feinstein alleged on Monday — that leaks of classified national-security information are coming from the Obama White House. But just last month, President Obama flatly denied this was the case,” Romney spokesman Ryan Williams said in a statement.

Democrats hit back by accusing Romney of selectively criticizing the Obama administration, and not past Republican administrations, for leaks.

In the MSNBC interview, Axelrod pointed to a statement from the Romney campaign Tuesday from Eric Edelman, a former undersecretary of Defense, that attacked Obama over the leaks.

Axelrod pointed out that Edelman was an aide to Vice President Dick Cheney’s aide Scooter Libby, and he was tied to the Valerie Plame leaks that occurred under the George W. Bush administration, a connection first reported by Buzzfeed on Tuesday.

“I don’t think they have a heck of a lot of credibility on this issue,” Axelrod said.

Democrats and the Obama campaign argue that Romney is using the issue as he departed Tuesday for a foreign-policy trip to try and distract from his lack of national-security experience and specifics on policy.

Obama leads Romney in polling on foreign policy and national security, as he has a record to point to that includes the killing of Osama bin Laden, the end of the Iraq war and the drawdown in Afghanistan.

But Republicans strategists say that pushing back on leaks can be an effective way for Romney to gain ground on Obama over foreign policy.

“It’s part of a bigger narrative that this president is not all that he’s cracked up to be, on foreign policy or on anything else,” said John Feehery, a Republican strategist who writes a column for The Hill.

“It goes at the credibility of the White House and credibility of the president,” he said.

Republican lawmakers who attacked the White House over the leaks last month cheered Romney’s attacks. 

Republicans have homed in on Attorney General Eric HolderEric Himpton HolderFlake's anti-Trump speech will make a lot of noise, but not much sense Former Fox News correspondent James Rosen left amid harassment allegations: report Issa retiring from Congress MORE not appointing a special counsel, instead tapping two U.S. attorneys to investigate. The lawmakers have accused Holder of being unable to lead an independent investigation of the administration, and in his speech Tuesday, Romney joined their call for a special counsel.

Led by Sens. John McCainJohn Sidney McCainMcCain rips Trump for attacks on press NSA spying program overcomes key Senate hurdle Meghan McCain says her father regrets opposition to MLK Day MORE (R-Ariz.) and Lindsey GrahamLindsey Olin GrahamDHS chief takes heat over Trump furor Overnight Defense: GOP chair blames Dems for defense budget holdup | FDA, Pentagon to speed approval of battlefield drugs | Mattis calls North Korea situation 'sobering' Bipartisan group to introduce DACA bill in House MORE (R-S.C.), Republicans allege that the leaks came from the White House for political gain.

“Give me a break,” Graham told The Hill when asked about Axelrod’s comments. “I don’t buy it one bit, and I don’t believe they should be able to investigate themselves.” 

House Homeland Security Chairman Pete King (R-N.Y.) told The Hill that he wished Romney would have spoken up about the leaks sooner.

“To me it’s a necessary part of the presidential debate,” King said. “I would say that politically to show that an administration is either negligent or willfully leaking national-security secrets is disgraceful.” 

Democrats were less concerned about the impact the leaks could have on the campaign. Like Axelrod, Senate Armed Services Committee Chairman Carl LevinCarl LevinCongress: The sleeping watchdog Congress must not give companies tax reasons to move jobs overseas A lesson on abuse of power by Obama and his Senate allies MORE (D-Mich.) pointed to the Bush leaks on Tuesday, and suggested that even some of the recent leaks originated from that administration.

Larry Korb, a defense analyst at the liberal-leaning Center for American Progress, said the Republican attacks on Obama over the leaks were “nonsense.”

“Things get out in all administrations — it happens,” he said. “I don’t’ think it’s going to resonate in terms of the politics or whether people are going to vote.”

Feinstein’s comments this week suggesting some leaks came from the White House complicate the issue for the Obama campaign, as Romney can rely on those remarks for backup. 

Feinstein said in her statement Tuesday she regretted her words were being used to attack Obama, and said she should not have speculated about the source of the leaks when she did not know. 

The Senate Intelligence chairwoman was not commenting further Wednesday, giving a polite “no comment” when asked by The Hill to elaborate on her statement. 

Jonathan Easley contributed