For the first time in his presidency, Americans are getting a glimpse of Barack Obama on defense.

Over the past few weeks, Obama has been back on his heels over torture and terror, issues on which he surely thought he had the upper hand.

And he spent Thursday battling charges from a man he surely thought he had vanquished in November, former Vice President Dick Cheney.

It took some worried calls from Capitol Hill Democrats, congressional aides said, to convince him otherwise – that he needed to give a speech defending his plan for closing the terror prison at Guantanamo Bay, and rebutting Republican claims that the move would endanger Americans where they live.

Senate Majority Leader Harry Reid and others made clear “that we’re going to need a lot more cover if we’re going to be able to deal with this issue,” said one Democratic leadership aide.

So on a day when Obama would have rather been anywhere else – remaking the auto industry or cheerleading an economic recovery – he was sharing TV screens with Cheney, the two men equals, at least for one hour.

“The White House didn’t want to do it — they want to drive the agenda, they want to be focused on health care right now,” said Heather Hurlburt, the executive director of the National Security Network, a Democratic think tank. “The Hill asked him to do this and he did it.”

That forcing of Obama's hand marks a remarkable turnabout for a president who holds the most commanding position in American politics in two decades.

The most popular politician in the country found himself pushed up against a wall by one of the least popular in Cheney – the leading voice in a budding Republican attack on Obama over national defense, one of the GOP’s oldest (and most successful) cudgels against Democrats.

With some Democrats worried that Cheney is building a case to blame Obama if the United States is attacked again, the new president argued on Thursday that the former vice president's ideas for harsh interrogations and holding prisoners indefinitely made the nation less safe, not more.

White House officials deny that they felt any pressure from Cheney’s prior attacks to give a speech like the one he delivered on Thursday, but they did concede that Obama’s stance has been distorted in the debate over terrorism.

Congressional Democrats, however, tell a different story. Aides to top Senate and House Democrats say congressional leaders dragged the White House into delivering a speech Obama was reluctant to give, pleading directly with White House Chief of Staff Rahm Emanuel. They warned of the revolt that finally materialized Wednesday when a solid Democratic majority in the Senate was stampeded into a landslide 90-6 vote against the president on funding the closure of Gitmo.

“He was responding to signals coming from the Hill in recent weeks that intensified in recent days,” said the Democratic leadership aide. “I’m not quite sure how we got into this situation, and I’m not sure what the hesitancy was on the part of the administration.”

And even the speech, which stopped short of laying out a detailed plan for the Guantanamo detainees, left some frustration among congressional leaders.

“In our perfect world, he would have given this speech before the vote [on stripping funding to close Gitmo]. It was a good speech, but there weren’t enough specifics in it that he couldn’t have nipped this in the bud last week or the week before,” said another leadership aide.

The pressure on Obama has built steadily since Jan. 22, when he announced his plan to close the detention center at Guantanamo Bay. It intensified when the White House showed rare uncertainty in the debate over torture, sending mixed signals on the prosecution of former Bush administration officials.

Obama intensified the debate, and inadvertently snared House Speaker Nancy Pelosi, by releasing a set of memos written by Bush administration lawyers justifying harsh new interrogation practices, a move some senior aides now see as a political error.

Meanwhile Cheney attacked, and congressional Republicans, led first by Senate Minority Leader Mitch McConnell, began trooping daily to the House and Senate floor to warn their constituents that they should soon expect to meet Khalid Sheikh Mohammed in the sporting goods aisle at Wal-Mart. In early May, they introduced the provocatively named Keep Terrorists Out of America Act.

Terrorism has, after a quiet period, made its way back into the headlines, with news this week of a disrupted plot in New York and of released detainees returning to the battlefield.

The White House could no longer avoid the subject.

Cheney is “totally unpopular, and was thoroughly repudiated at the polls in November – but now he’s setting the terms of the debate,” said Rep. Peter King (R-NY), the ranking Republican on the Homeland Security Committee. “I don’t think [the White House] ever thought they’d be on defense on Guantanamo.”

“I think they must feel from a political point of view that he’s losing control of this issue, and it may have been a political overreaction,” King said of the speech.

Cheney’s deep unpopularity, Democratic leaders believe, also provides Obama a perfect opportunity to bolster what polls suggest is already broad public trust in his handling of national security issues.

“Every night when you hit your knees, thank God for Dick Cheney,” Democratic consultant Paul Begala said he’d advise Obama.

Mary Matalin, a former aide to Cheney, said the speech had tilted too far in the direction of pleasing the Democratic left.

“Whatever he may have accomplished with his base, he lost in the big middle,” she said in an e-mail. “People know the threat is still out there (hello! N.Y. arrests; Iran missile launch; today’s news) and they do not think calling it what it is is ‘fear-mongering.’”

The speech’s effectiveness, however, will be measured by whether he retains his ability to reshape a charged debate.

In some 6,000 words Thursday, Obama used a characteristic tactic: He sought to reclaim the issue of Guantanamo detainees by broadening it into a larger discussion of American values and national security. It was same tactic he used when, just over a year ago, political foes and critics put his back against the wall with video of racially charged speeches by his former pastor, and the Illinois senator responded with a broad and effective thematic speech on his personal narrative, race and America.

Congressional Democrats seemed to have found at least some of the cover they sought Thursday.

“I think [what] the president did today is give us a broad vision about what he expects,” Reid said. “He is going to give us a detailed plan.”

Civil libertarians attacked some details of the plan – the ACLU called a sketchy discussion of indefinite detention “troubling” – but the speech, and the confrontation with Cheney did serve the side-purpose of bringing Congressional liberals back to the fold.

They were quick to praise both the speech and the president’s rededication to their priorities.

“The two speeches offered a stark and revealing contrast — the president wants to protect the country while upholding and strengthening our time-tested constitutional principles, while the former vice president offered the same misleading scare tactics and flawed approach to national security that Americans repudiated in the last election,” Sen. Russ Feingold said in a statement about Cheney’s and Obama’s speeches.

Rep. Jerry Nadler (D-N.Y.), who is leading the charge for investigating Cheney, called Obama’s speech “powerful.”

“There are some areas where he didn’t go into detail, but I’m very hopeful, given his recognition of civil liberties and values questions,” he said.

Will Marshall, a centrist national-security expert at the Progressive Policy Institute, said Obama had been feeling the heat from his own base.

“He’s asking the left to trust him and to understand that this is really different, because he’s making a good faith effort to reconcile values and security, while the Bush administration didn’t,” said Marshall.

But it may be Obama’s greatest political gift to leave different audiences hearing different things in a speech of detailed, nuanced words. A longtime observer of national security politics, former Nebraska Sen. Bob Kerrey, said he was struck by the similarities between Thursday’s speeches.

“There’s a lot of overlap between what Cheney said and what Obama said. ‘Al Qaeda has declared war on the United States.’ Both of them said that. ‘It’s an existential threat.’ Both of them said that. And you’ve got to respond with force. Both said that.”