President Barack Obama declared again Monday that he'd like a really big deficit-cutting deal—and for good reason. He, more than most Democrats, has powerful incentives to seek a big strike against deficits right now.

Speaker John Boehner discusses the deficit talks Monday in the Capitol. Reuters

That reality explains a lot about what has been going on behind the scenes in the current Washington psychodrama, which so far has played out mostly on Republican turf.

The broad contours of this drama are by now well known: To win the votes in Congress to raise the government's debt ceiling so Washington can keep paying its bills, Democrats and Republicans first need to agree on a plan to cut deficits. While Vice President Biden and some key members of Congress have been in one room in recent weeks negotiating a deal to cut deficits by about $2.4 trillion over the next decade, Mr. Obama and Republican House Speaker John Boehner have been, in effect, off in another room talking about a much bigger, historic deal to cut deficits by $4 trillion, while starting to overhaul the tax code and the Medicare system in the process.

That effort appeared to collapse during the weekend when Mr. Boehner decided he couldn't swallow the $1 trillion of revenue and tax increases Democrats considered necessary to strike the deal, and Mr. Obama wouldn't move off that position. Still, Mr. Obama sounded Monday like a leader who still very much wanted to keep the big idea alive: "I continue to push congressional leaders for the largest possible deal," he said before a new round of talks with those congressional leaders.

And for good reason. Though in the climate of suspicion that permeates Washington some doubt the president genuinely wants the big strike at deficits he's trumpeting, he actually has plenty of incentives to seek that kind of deal. The President Obama who entered office 30 months ago wasn't a deficit cutter by instinct, but today's version has learned the hard way that he needs to become one.

The president's most recent speech was an attempt to calm the public as a vote over the debt ceiling stalled. David Wessel and Alan Murray analyze whether the speech will be enough to placate the public and spur action in Washington.

Let's stipulate at the outset that both Messrs. Obama and Boehner have been searching for a big deficit deal for the most important reason of all: Both think one would be good for the country and its economy in the long run. Both deserve credit for that.

Beyond that, deficit cutting is good politics for Mr. Obama right now and as he seeks re-election next year. Many Americans fear their country is out of control, which isn't a good environment for any sitting president. To the extent rising deficits and growing debt contribute to that feeling, reversing the trend line in a dramatic way would be a good thing.

That's less true for congressional Democrats, who worry more about protecting entitlement programs and domestic spending beloved by their party's base. But for a president eager to win back independent swing voters, deficit cutting is a net plus. It's worth noting that the biggest influences on the president as he navigates this issue are Treasury Secretary Tim Geithner and White House political adviser David Plouffe, both of whom are convinced, for different reasons, of the virtues of deficit cutting.

Mr. Obama also knows that, in any deficit-cutting deal large or small, he's going to suffer with senior citizens, a group with which he already has problems. Even a smaller deficit deal will require some trimming in Medicare spending. Democrats will pounce, and Mr. Obama will have to absorb it.

So from Mr. Obama's perspective, if you're going to take the pain for a deficit deal anyway, you might as well get real gains along the way. In a phrase Mr. Biden has been using, "There's no point in dying on a small cross." That explains why Mr. Obama has been prepared to discuss with Mr. Boehner significant changes in how Medicare functions, including the possibility of adjusting the age of eligibility.

A big deficit deal also would allow Mr. Obama to say to Democratic constituencies that, even if they're unhappy with him, he at least put their most cherished programs—Medicare and Social Security—on sounder financial footing for a generation to come.

But perhaps most important, the big deal would clear the decks for Mr. Obama to focus on other pursuits, without having deficit problems constantly nipping at his heels. If he wins a second term, you can be sure he would rather think about alternative energy, education and immigration than be nicked and cut at every turn by deficit problems.

So those are the factors motivating Mr. Obama. But how would he handle a failure to get that big deal?

For starters, his talking points practically write themselves: I offered three dollars in spending cuts for every dollar in tax increases, and Republicans turned me down. Because Republican leaders wouldn't accept any tax increases, everybody will pay more for Medicare and Social Security and get less in benefits down the road.

And ultimately Mr. Obama has one time-honored tactic at his disposal: He can use failure to run, Harry Truman-style, against a "do-nothing Congress."

Write to Gerald F. Seib at