Apparently, fillibuster rule can be changed with a simple majority:
NY TimesIssuing a blunt warning to Democrats, the Senate majority leader, Bill Frist, said Thursday that the newly strengthened Republican majority would not allow filibusters to block action on judicial nominees in President Bush's second term.
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Senator Trent Lott, the Mississippi Republican who is chairman of the Rules Committee, has been among the Republicans who have also suggested that the Republicans try to win a change by seeking a ruling from the chairman, a position that a Republican would hold, that filibusters against executive nominations are unconstitutional. A favorable ruling would require just a majority to uphold.
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"To implement it would make the last Congress look like a bipartisan tea party," Senator Charles E. Schumer, the New York Democrat who is on the Judiciary Committee, said. "For the sake of country and some degree of comity, I would hope and pray that the majority leader would not take away the Senate's time-honored, 200-year-old tradition."