Now that Congress has gotten past the fight over a threatened government shutdown, it's moving on to the next trench warfare on deficit reduction, with more clouds of calamitous stalemate hanging over it.

Just as in that first fight, House Speaker John Boehner is embarking on political blackmail to achieve deeper spending cuts, saying categorically that the House majority will not raise the federal debt limit on which U.S. global credibility rests unless the Democrats agree to much more severe budget slashing.

At the same time, Mr. Boehner says he agrees absolutely with President Barack Obama that the federal government cannot be allowed to default on its worldwide fiscal obligations, which would send interest rates skyrocketing and kick off another economic crisis here and abroad.

The speaker thus is assuming the same opening-round posture he took in his rigid insistence for $60 billion in deficit reduction in the threatened shutdown, which fell to about $38 billion in the ultimate compromise that kept the government working. Though Mr. Boehner got far more than the Democrats indicated at the outset they would swallow, his threat inevitably lost some of its credibility in the deal struck.

Similarly, his latest insistence that the House Republicans will balk at raising the debt limit unless Mr. Obama agrees to more significant spending reductions isn't likely to carry as much political clout the second time around. Also, the mini-revolt of the tea party loyalists and others in his House majority on the shutdown vote laid bare Mr. Boehner's dependence on Democratic votes to get the compromise through.

Some 59 Republicans, one-quarter of the House majority, voted no, obliging the speaker to rely on 81 Democrats to go along behind House Minority Whip Steny Hoyer of Maryland (but not Minority Leader Nancy Pelosi, who dug in her heels against the negotiated spending cuts).

Mr. Boehner sounded somewhat restrained in observing that he and his party had captured the battleground by turning the national discussion more emphatically toward debt reduction. Of the way the government shutdown was averted, he said: "Is it perfect? No. I'd be the first to admit it's flawed. But welcome to divided government."

The comment was an acknowledgment that for all Mr. Boehner's political muscle flexing and success in raising himself to major-player status with the president of the United States in the current debate, he still leads only one of the three principal legs of the power equation in Washington. The other two, the White House and Senate, remain in Democratic hands.

Alongside Mr. Obama and Mr. Boehner, Senate Majority Leader Harry Reid is coming off as a lesser force in this split government, despite the fact that the slim Democratic majority in the Senate remains a firewall against deeper Republican cuts. This was especially so after the president moved from the sidelines in the fight over the government close-down and now has jumped with both feet into confrontation with House Budget Committee Chairman Paul Ryan over his broad deficit-reduction plan.

Mr. Obama, after so forcefully challenging the Ryan plan in his major speech on budget-cutting in Washington last week, repeated some of its key points on the 2012 campaign trail the next day in Chicago, in his first stump appearance since the formal announcement of his bid for reelection.

In his attack Wednesday on Mr. Ryan's proposal, he had charged that "this vision is less about reducing the deficit than it is about changing the basic social compact in America" embodied in the social safety net that has been cornerstone of Democratic defense of the middle class and the poor.

In Chicago on Thursday, Mr. Obama said: "We can get our fiscal house in order, but we can do it in a way that is consistent with our values and who we are as a people. Or we can decide to shrink our vision of what America is. And I don't believe in shrinking America. That's not who we are."

Mr. Ryan, who attended the Washington speech at the invitation of the White House, later expressed anger at what he called an "extremely political, very partisan" speech not conducive to future conciliatory budget discussion. But as Mr. Boehner himself put it, welcome to divided government.

Jules Witcover is a syndicated columnist and former longtime writer for The Baltimore Sun. His latest book is "Joe Biden: A Life of Trial and Redemption." His email is juleswitcover@comcast.net.