Senate Democrats decided Thursday not to release their spending plan to counter the budget blueprint approved last month by House Republicans, saying they will wait to see whether talks at the White House produce a compromise plan for reining in the national debt.

Democrats said they are close to agreement on a spending plan that would reduce borrowing by more than $4 trillion over the next decade, with about half the savings coming from higher taxes. That would offer a sharp contrast to the GOP budget, which relies entirely on deep cuts in spending.

But rather than subject a proposal for higher taxes to Republican attack, Senate Budget Committee Chairman Kent Conrad (D-N.D.) said he would “defer” action “because of the high-level bipartisan leadership negotiations that are currently underway” involving lawmakers from both parties and Vice President Biden.

“If you go through a partisan markup, it hardens people’s positions and makes it more difficult to get a bipartisan agreement,” said Conrad, a member of the Senate’s Gang of Six, which has been trying to draft its own debt-reduction framework.

“After four months in the group of six, trying to reach a bipartisan agreement is as difficult as anything I’ve ever been involved in,” Conrad said. “I want to give every chance for a bipartisan agreement to succeed.”

Republicans mocked the decision, noting that Democrats are deeply divided over how much to cut spending and whether to raise taxes at all, much less adopt one alternative under discussion: a surcharge on millionaires. Republicans called the delay a ploy to avoid making hard decisions.

“First, Senate Democrats offered the excuse that they were waiting for the Gang of Six. Now we are told they are waiting on the Biden talks. But there is no reason to believe the Biden talks will be any more successful than the Gang of Six,” said Sen. Jeff Sessions (Ala.), the senior Republican on the Senate Budget Committee, who has been hammering Democrats daily for their failure to draft a spending plan for fiscal 2012.

Senate Majority Leader Harry M. Reid (D-Nev.) “may wish to shield his members from tough votes that expose their unwillingness to cut spending or their eagerness to raise taxes. But that strategy will not hold,” Sessions said in a statement. “The public will be mobilized.”

While participants say the Biden talks are making progress toward a long-term debt-reduction strategy, the Gang of Six has been downgraded to a Gang of Five since Sen. Tom Coburn (R-Okla.) pulled out this week, citing an impasse with Democrats over how deeply to cut Medicare. Coburn described himself Thursday as being “on sabbatical” from the group. Some Republicans are pushing him to rejoin the effort, saying a bipartisan plan cannot win significant GOP support without his endorsement.

A meeting of the remaining Gang of Five — now two Republicans and three Democrats — was canceled Thursday, and the future of the effort is unclear, as attention has shifted to the negotiations led by Biden.

In addition to the political reasons for waiting to see whether the Biden talks produce an agreement, Conrad said there are procedural reasons as well. Budget deals in 1990 and 1997 relied on a special fast-track process known as reconciliation to push debt-reduction plans through Congress, he said.

Reconciliation bills, which cannot be filibustered in the Senate, are authorized through a budget resolution. Approving a budget resolution now, Conrad said, could make it more difficult to use reconciliation and, therefore, to implement any bipartisan deal.

“We are going to have a budget at the end of the day here,” Conrad said. “But it makes no sense to run a partisan markup at this moment.”