The emerging line on this week’s activities in the Senate is that the confirmation of Obama nominees in the wake of the GOP cave in the nuclear showdown shows Mitch McConnell has lost control of his caucus. This may well be a premature judgment. But this morning brings fresh signs Dems are prepared to do all they can to exacerbate the emerging schism among Republicans.

I noted here yesterday that Dems are gearing up to use the coming battle over the transportation and housing bill to test whether Republican Senators will continue to break with the GOP leadership and the Senate’s hard right bloc. Meanwhile, Politico reports that Dems are already looking forward to other coming battles as a further test of faltering GOP unity.

The key is that the emerging group of Senators who want to find a way to cooperate with Obama and Democrats — John McCain, Bob Corker, and others who have been meeting with White House officials to discuss ways of cooperating on the budget — are likely to run headlong into the intransigence of House Republicans:

The GOP factionalism could become even more significant this fall when it’s time to cut deals with Senate Majority Leader Harry Reid and the White House on boosting the debt ceiling and keeping the government operating past September…McCain wants to see Senate Republicans negotiate with Democrats on these critical matters, but there are a number of GOP conservatives — especially in the House — who are prepared to shut down the government or default on the debt unless Obama caves to their spending demands.

These House Republicans, of course, are joined by some Republicans in the Senate who — for various reasons, such as reelection pressures, a continuing desire to appeal to the GOP base, etc. — are opposed to compromise. This quote from Senator John Cornyn — a member of the intransigent bloc — perfectly captures the fault line between these two groups:

Already, the fault lines are showing. McCain and Sen. Lindsey Graham — more focused on the Pentagon’s needs — are open to Democratic demands for new tax revenues if they get a deal to shut off the automatic spending cuts known as the sequester. Cornyn flatly rejected that idea on Thursday.

“We’d all love to have a grand bargain, but not on the president’s terms – which is more taxes after a $600 billion tax increase in January,” Cornyn said.

And there you have it. Obama and Democrats want to reach a deal on the budget, and perhaps replace the sequester, with a compromise — a mix of spending cuts and tax hikes — but to Cornyn, compromising itself constitutes doing a deal “on the president’s terms.” In other words, any compromising by Republicans is tantamount to surrender to the president — even if Republicans get something in return, such as the entitlement cuts that they say they want and that the president has offered them — and is therefore unacceptable.

This is the fundamental problem Democrats face, and they have to hope that there are enough Senate Republicans out there who are fed up with this basic posture. This week’s activities suggest reason for a glimmer of optimism. It’s going to be very interesting to see what McCain, Graham, Corker, and the others have to say in coming days about whether Republicans should be willing to accept the need for new revenues as part of any fiscal deal. Even more interesting to hear will be what members of the Compromise Caucus have to say about continued GOP demands for concessions in exchange for the debt ceiling hike that everyone knows is going to take place anyway.

*TURBULENCE IN SENATE GOP CAUCUS CONTINUES: The New York Times confirms what Roll Call reported yesterday: Republican Senators are challenging Mitch McConnell’s efforts to distance himself from the deal Dems won to get Obama’s nominations passed, claiming he was involved in the talks every step of the way. Republican Senators are angry with the deal, claiming they got “rolled” by Dems, because they got nothing in exchange for allowing Obama’s nominations to go forward — not even a promise that Dems won’t go nuclear in the future.

So, again: Is Mitch McConnell losing control of his caucus? Too early to say — but watch what happens next week around the transportation bill.

* SENATOR WHO CHALLENGED MCCONNELL STANDS FIRM: Bob Corker, one of the Senators who broke with the leadership on the filibuster deal, offered an interesting defense of his move:

“What I did yesterday was not in a vacuum and I’m glad to be able to be in a position where I can do things that are for the greater good of the Republican Conference, the U.S. Senate, and ultimately, candidly, for the country and that’s what I did yesterday.”

So breaking with the GOP leadership’s relentless obstruction was necessary for the good of the country? Good to know.

 * OBAMA GRAPPLES WITH UNPRECEDENTED CHALLENGES ON HEALTH REFORM: Don’t miss Karen Tumulty’s excellent overview of how Obama’s effort to implement the Affordable Care Act faces unprecedented challenges, from the complexity of the law to the refusal of GOP lawmakers to help their constituents benefit from it. This is key:

Some Republican lawmakers, who routinely help their constituents with concerns about Social Security and Medicare, have even served notice that they do not plan to assist those who come to them for aid in navigating the new health-care system.

There will come a point at which this position becomes untenable, meaning Republicans will probably have to accept the need to help implement the law eventually; the question is how long it will take.

* CAMPAIGN TO SELL OBAMACARE KICKS INTO HIGH GEAR: National Journal has a good report on how Obama and outside allies are gearing up their campaign to sell Obamacare to the public in the face of ceaseless attacks on the law — and outright efforts to sabotage it — from Republicans. The key point is that for politicians such as Mitch McConnell (who faces reelection) and Marco Rubio (who needs to compensate for his apostasy on immigration), scorched earth resistance to Obamacare continues to be the best way to fire up the base.

And so the attacks will only keep coming — which means Obamacare’s supporters must, and will, continue to forcefully rebut them

* WEAK RECOVERY CONTINUES TO LEAVE MIDDLE CLASS BEHIND: A must read from Jim Tankersley on how economic indicators show that the recovery is doing little to help working Americans, whose incomes continue to lag, while mass unemployment remains a serious crisis.

Despite this, the debate continues to be mired in questions about how much austerity we should continue to impose: hopes for replacing the sequester are slim, and at any rate only a deal largely composed of spending cuts elsewhere is feasible. Congressional action on jobs, obviously, remains a pipe dream.

* AND TODAY’S PLUM READS:

After a video of Elizabeth Warren demolishing a CNBC anchor in an exchange over the virtues of financial regulations went viral, CNBC apparently responded by yanking it on copyright grounds.

* David Lightman on the increasingly tough political road Mitch McConnell faces as he’s caught between the growing rift in his caucus and his own reelection challenge.

Adam Serwer notes that Thomas Perez waited a year to get confirmed as Labor Secretary, and explains why Republicans simply can’t drop their ideological hostility to the guy.

Wonkblog has a nice roundup of all the news showing that not only is Obamacare not a train wreck, the “Obamacare trains are running on time.”

Jonathan Chait on Politico and the real problem with Washington.

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.