Washington (CNN) -- The Senate will begin debate on ratifying a new nuclear arms treaty with Russia as soon as Wednesday, after the chamber passes the tax package that President Barack Obama negotiated with Republicans, Senate Majority Leader Harry Reid said Tuesday.
Asked if he had the 67 votes necessary for ratifying the START accord, Reid told reporters he did.
Some Senate Republicans, led by conservative Sen. Jon Kyl of Arizona, have opposed bringing up START -- the Strategic Arms Reduction Treaty -- with so little time left in the congressional session.
Kyl told CNN on Tuesday that "it would be a big mistake" for the Senate to begin debate on the treaty Wednesday. Asked if he had the votes to block ratification, Kyl responded: "I've given Majority Leader Reid my best judgment as to what the situation is and why it would be a mistake to bring it up."
Reid said the Senate will take up both the START agreement and a vital government spending resolution in the final days of the current lame-duck session of Congress. The current resolution authorizing government spending runs out on Saturday, requiring congressional approval of a new one to cover the rest of the fiscal year.
In addition, Reid said he wants the Senate to also consider an immigration bill opposed by Republicans and a measure that would repeal the "don't ask, don't tell" policy barring openly gay and lesbian soldiers from the military.
He warned Republicans he would keep the Senate in session for as long as it takes, including up to and even beyond Christmas, in order to take up the measures before the end of the current lame-duck session of Congress. A new congressional session with a diminished Democratic majority in the Senate and Republican control of the House begins on January 4.
"I want to get out of here just as soon as we can, but we're not going to walk away from any of the work that we have to do," Reid said. He added that he understood Christmas was less than two weeks away, but noted: "There's still Congress after Christmas."
However, Senate Republicans complained that Reid's plan would rush through measures without proper consideration and debate. In particular, Sen. Mitch McConnell of Kentucky, the GOP Senate leader, told reporters he opposed a Democratic plan to pass a $1 trillion spending resolution to keep the government in operation for the rest of the current fiscal year.
Instead, McConnell called for extending government spending at current levels for a few months and letting the new Congress that takes office in January take up further spending resolutions until the fiscal year ends on September 30.
The Senate Foreign Relations Committee voted for ratification of the new START accord in September, but a vote from the full Senate has yet to occur. The treaty would resume mutual inspections of U.S. and Russian nuclear arsenals, while limiting both nations to 1,550 warheads and 700 launchers each.
Ratification requires support from two-thirds of the Senate, or 67 votes. Democrats currently control 58 seats and need nine Republicans for ratification. In the new congressional session, the Democrats will only have 53 seats and would need 14 Republican votes to ratify the treaty.
Obama predicted last week that the Senate would take up the treaty before the end of the year, based on a conversation he had with McConnell.
White House Press Secretary Robert Gibbs said Friday that the chamber would remain in session this year for as long as necessary to ratify the START agreement.
Gibbs made his prediction on the same day that Maine's two moderate Republican senators -- Olympia Snowe and Susan Collins -- declared their support for the new treaty. Previously, Sen. Richard Lugar of Indiana, the ranking Republican on the Senate Foreign Relations Committee, backed ratification of the treaty.
In addition, Republican Sen. John McCain of Arizona also said he wanted to see the treaty ratified, but questioned if there was time to do it this year.
"We're going to get more than 67 votes," Gibbs told reporters, adding: "Congress won't leave before START is done, START will get done, and START will get done with a strong bipartisan vote."
In a recent Washington Post editorial, five big guns of Republican foreign policy -- former Secretaries of State Henry Kissinger, George Shultz, James Baker, Lawrence Eagleburger and Colin Powell -- urged their fellow Republicans to support the treaty, which they say is "is clearly in our national interest."
CNN's Ted Barrett and Tom Cohen contributed to this report.