By Joseph J. Schatz, CQ Staff

President Obama’s efforts to stake out the political middle ground in debt limit talks are drawing behind-the-scenes warnings from Democratic leaders, whose support will be critical to passing a deal.

With just a few weeks before the nation defaults on its financial obligations, Obama must weigh the viability of a deficit reduction package including more than $1.7 trillion in spending cuts. From the right, the president still faces pressure to keep taxes out of the deal; from the left, restive lawmakers increasingly push for new revenue and decry plans to pare entitlements.

Based on earlier negotiations led by Vice President Joseph R. Biden Jr., the cuts being considered would trim more than $1.1 trillion from discretionary spending and hundreds of billions of dollars from Medicare and Medicaid.

But heading into a third straight day of talks between Obama and congressional leaders at the White House, Democratic leaders in both chambers are warning Obama that such a package risks losing support from their caucuses.

Late Monday, a House Democratic leadership aide said party leaders are telling the White House that members of their caucus will not vote for a deal consisting entirely of spending cuts, without any revenue increases.

And according to another source familiar with the talks, Senate Majority Leader Harry Reid, D-Nev., said at the Monday meeting that the $1.7 trillion package of cuts, with its entitlement reductions, would not be able to pass the Senate.

Another problem for debt negotiators: The cuts under consideration might not be large enough to cover the cost of a longer-term debt limit increase.

House Republican leaders are demanding that any increase in the $14.3 trillion debt ceiling be matched or exceeded by accompanying spending cuts. The $1.7 trillion package of cuts could fall short of the $2.4 trillion increase in the debt limit necessary to carry the government through the coming election — a key White House goal.

Yet they would come close. And even as Obama publicly pushes Republicans to accept new revenue as a price for entitlement cuts, he also has made it clear that he is willing to go to the right of some congressional Democrats when it comes to reducing entitlement spending.

“The vast majority of Democrats on Capitol Hill would prefer not to do anything on entitlements,” Obama said in a White House press conference Monday. “If you look at the numbers and Medicare in particular we’ll run out of money, and we will not be able to sustain that program.”

Democratic votes will be critical to passing a deficit reduction package in both chambers; even in the Republican House, Democratic votes will be necessary to offset the expected opposition of many conservatives to any debt limit increase. Still, Obama may end up breaking with many of his Democratic allies in the interest of securing a deficit reduction deal heading into his 2012 re-election bid.

Attention has shifted back to the substance of the earlier Biden discussions after House Speaker John A. Boehner, R-Ohio, said July 9 that a larger, $4 trillion deficit reduction package would not work because of House GOP resistance to revenue increases.

While Senate GOP leaders have floated the idea of a short-term debt limit increase to buy time for a larger deal, Obama dismissed that idea Monday, saying he would not sign a 30-, 60- or 90-day debt limit increase.