Partisan tensions were flaring ahead of a critical summit Sunday evening at the White House, where aides say President Obama plans to make one last push for a major deficit-reduction deal amid doubts on both sides. 

Fox News has confirmed that the talks are still on despite a surprise announcement from House Speaker John Boehner that rattled the almost-optimistic mood surrounding the negotiations. 

The speaker, claiming the White House was pushing too hard for tax hikes while not pushing hard enough for entitlement reform, said Saturday evening that lawmakers should aim for a smaller deficit-reduction deal. Instead of the $4 trillion package officials were talking about just days ago, Boehner suggested negotiators aim for a deal that would be worth about half that over the next decade. 

Senate Republican Leader Mitch McConnell, speaking on "Fox News Sunday," confirmed that a $4 trillion package is now off the table. 

"Everything they've told me and the speaker is that to get a big package would require big tax increases in the middle of the economic situation," McConnell told "Fox News Sunday." 

Earlier in the week, Democrats had been sparring with the White House over its perceived willingness to deal with the GOP on entitlement reform. But Boehner's statement on Sunday turned their focus back to hammering Republicans for their insistence on no tax hikes in the deficit talks. 

"All they want is to cut Medicare/Social Security and protect the rich," a senior Democratic congressional aide told Fox News. 

Rep. Xavier Becerra, D-Calif., said there must be "shared sacrifice" in any deal. 

"Everything has to be on the table. But pretty quickly, my Republican colleagues said, everything should be on the table except taxes. That doesn't seem fair," he told "Fox News Sunday." 

On the other side, Sen. Jim DeMint, R-S.C., accused Obama of "gaming Republicans." 

"It's hard to take him seriously here," he said on "Fox News Sunday." 

The partisan recriminations cast a pall over the talks Sunday evening. After a bipartisan meeting at the White House Thursday, officials were talking ambitiously about a grand bargain -- one which might cut spending, address all three major entitlements, achieve tax reform and make other monumental changes in exchange for a "yes" vote on raising the $14.3 trillion debt ceiling before an Aug. 2 deadline. 

The fact that Republicans -- those pushing hardest for spending cuts and entitlement reform -- were scaling back those goals Sunday signaled the negotiations were still in a tenuous place. 

White House Chief of Staff Bill Daley nevertheless said Obama will push for a big deal out of Sunday's meeting. 

"Everyone agrees that a number around $4 trillion is the number that will make a serious dent on our deficit," Daley said. "That's what he wants to see. ... This president's still committed to doing big things." 

Daley, speaking on ABC's "This Week," called Boehner's statement "unfortunate." 

Treasury Secretary Timothy Geithner reiterated Sunday that a failure to negotiate a package and raise the debt ceiling by Aug. 2 would have "catastrophic" consequences for the economy. 

However, he and other officials expressed confidence that no matter the course of negotiations, Congress will ultimately vote to lift the cap.