WASHINGTON (AP) _ The House and Senate, in the face of the government's worsening financial condition, launched a new battle over a balanced-budget plan that's blocking expansion of the Treasury's credit line.

The Senate resumed its debate today, but Senate Majority Leader Robert Dole, R-Kan., said the White House was expressing new concerns that possible defense cuts under the plan might undermine President Reagan's position in Geneva.

Congress' failure to raise the debt limit has already forced the Treasury to tap into the Social Security trust funds, costing $10 million in lost interest. Spending on some programs may be delayed if the situation continues, officials said.

If there's no action by Nov. 14, the Treasury will default, according to the Reagan administration.

House Speaker Thomas P. O'Neill Jr., D-Mass., on Monday blamed the Senate and Dole for the need to reach into the Social Security cash box.

''I think he (Dole) is playing a little politics with this and I guess he'd accuse me of doing the same,'' said O'Neill, telling reporters he had no plans to meet with Dole.

Dole, at a breakfast meeting with reporters today, said he favored even stronger action than Congress was contemplating to stop government red ink.

''If anything, this whole exercise has certainly made a case for a balanced budget (constitutional) amendment,'' Dole said. The weakness with any bill, he said, was ''when we get up to the crunch we can always change it.''

But he said the White House, despite Reagan's enthusiastic support of the bill, was contacting him and appeared to be getting fidgety.

''I think there's some concern about the President going to Geneva... he thought there might be some defense cuts looming,'' Dole said. ''It seemed to me a cursory examination of Gramm-Rudman three weeks ago might have led to that conclusion.''

O'Neill and Dole predict some version of the balanced-budget plan will pass despite partisan differences over the amendment.

''I don't think they (the differences) are that wide,'' O'Neill said.

The Senate last Friday refused to accept the House version of a short-term debt extension, even though that meant the divestment of Social Security holdings. Instead, the Senate passed its own version.

The Senate has refused to go along with a long-term increase of the government debt ceiling unless a balanced-budget plan is attached.

The Senate last month approved a plan to balance the budget by fiscal 1991. The proposal, sponsored by Sens. Phil Gramm, R-Texas, Warren Rudman, R-N.H., and Ernest Hollings, D-S.C., features statutory limits on red ink, enforced with automatic spending cuts if Congress fails to meet the targets.

Only Social Security, interest on the debt, and prior-year government contracts were exempted from the automatic cuts.

Gramm-Rudman, as the plan is known, raced through the Senate, passing 75-24, but then stalled in a House-Senate conference committee.

Last Friday, the House passed its own Democratic version that sponsors said would do the job quicker while being more fair to the poor.

On Monday, the Senate approved two Democratic-sponsored amendments - one would encourage Congress to toughen the minimum tax on corporations, while the other would change the automatic spending cuts in Gramm-Rudman during a recession.

The Senate is scheduled to vote on the bill again Wednesday, and leaders there intend to pass a modified version of the original Gramm-Rudman amendment. If the House doesn't go along with that, the conference committee may have to try it again.

The Treasury is at its credit limit of $1.824 trillion, and has asked for an increase to $2.078 trillion, enough to last through another year of $200 billion in deficit spending. The national debt has doubled since President Reagan took office.

The White House on Monday kept the focus on Congress' inability to agree on how to end the current cash crunch.

''Our position is that the Senate and House can resolve this; they can do so in 24 hours if they will get on the ball and do it,'' spokesman Larry Speakes said.