The Senate's bipartisan deficit reduction package faced a second day of assault Thursday after weathering two threats during a heated opening day of debate.

In a Wednesday session that lasted until midnight, the Senate fought off amendments to the deficit reduction that could have scuttled the plan, the major elements of which are favored by President Bush.The Senate defeated an amendment by Sens. Kent Conrad, D-N.D., and Max Baucus, D-Mont., to raise income tax rates for the rich to 33 percent from the current 28 percent and impose a 10 percent surtax on Americans whose annual taxable income exceeds $1 million. The defeated measure also proposed to hold the gas tax increase to 5 cents a gallon, down from the 9.5-cent hike contained in the bipartisan plan.

Later, Senate Democratic leader George Mitchell of Maine and Senate Republican leader Robert Dole of Kansas combined in a parliamentary maneuver to avoid a floor vote on an amendment offered by Sen. Steve Symms, R-Idaho, to remove the gas tax hike from the package.

The Senate bill would cut the deficit by $28.4 billion in fiscal year 1991, which began Oct. 1, and by $252.5 billion over five years. It is the cornerstone of the Senate's broader effort to cut the deficit by $40 billion in 1991 and by $500 billion over five years.

Senate debate on the deficit-cutting measure began a day after the House narrowly approved a plan crafted by Democrats.

Without agreement on a deficit-cutting plan, the government faces the possibility of another shutdown at 12:01 a.m. EDT Saturday. Bush has said he will not sign another emergency spending measure to fund the government without a budget accord in place.