WASHINGTON — For Senate Democrats, the magic number is six.
That's the number of Republican senators Democrats need to persuade to cross party lines if they want to win a potential showdown on changing the rules for selecting federal judges. And by most accounts, they are getting close.
That may be one reason Senate Majority Leader Bill Frist (R-Tenn.) tried to sound conciliatory Tuesday.
"We need to lower the rhetoric," Frist told reporters after his weekly luncheon with Republican senators, adding that he would offer a compromise "in the near future."
Frist refused to say whether he had the needed support to change Senate rules to make it impossible for Democrats to use filibusters to block votes on controversial judges.
"I'm just not going to go there," he said.
A filibuster is a parliamentary tactic in which senators can talk as long as they like to prevent a vote.
The arithmetic is fairly straightforward. Frist says he needs 51 votes to change the filibuster rule, and there are 55 Republicans in the Senate. One of those votes can come from the vice president, who as president of the Senate can vote to break a tie. That means to win the fight, Frist may be able to change the rules if he loses five senators; Democrats can win if he loses six.
Two Republicans -- John McCain of Arizona and Lincoln Chafee of Rhode Island -- have said they will vote with the Democrats against the rules change. Four other senators have said they have concerns about changing the rules and are considering voting against it. They are Olympia J. Snowe and Susan Collins of Maine, John W. Warner of Virginia and Chuck Hagel of Nebraska. More are rumored to be privately opposed but fear voting against their leaders.
Seeking to win their support, Democratic leaders divided Republicans into what they called "responsible" and "radical" members of the GOP.
"Responsible Republicans in this country and in this Senate must listen to what's going on in our country," Senate Minority Leader Harry Reid of Nevada told reporters after the weekly Democratic luncheon.
Reid referred to comments by former Senate Majority Leader and Republican presidential candidate Bob Dole, who told National Public Radio earlier in the day that "you have to be very careful ... before you start tinkering with the rules" because one day Republicans will be in the minority and need to use the filibuster.
"I served with Sen. Dole. He would never, ever consider something like this, because he believes in our institution. He would not be driven by the radical Republicans," Reid said.
Democrats contend that unlike the House, the Senate was designed by the founding fathers to be a forum that decided issues more on consensus, not strictly by majority rule. They say that they have approved 205 of 215 judges nominated by President Bush, but chose to filibuster 10 they considered extremist. They accuse the president of violating precedent by refusing to confer with them on potential nominees and by renominating seven of the 10 they oppose.
Republicans contend that the Constitution requires the Senate to provide its "advice and consent" on federal judges and that using filibusters on their nominations is therefore unconstitutional.
"All of you know that we're struggling right now with an assault on over 220 years of Senate tradition by the Democrats filibustering circuit court nominees, thus denying us the reasonable responsibility of an up-or-down vote to give advice and consent," Frist said.
Reid suggested that Republicans might be wrong about needing 51 votes to change the rules. Reid said he had discussed the matter with the nonpartisan Senate parliamentarian, Alan Frumin, who said that a rules change needed 67 votes.
"It takes a two-thirds vote to change a rule.... [Frumin] said that if they do this, they will have to overrule him because what they're doing is wrong," Reid said.
Frist and other Republicans contend that changing the filibuster rule would apply to only judicial nominees and would not affect the right of the minority party to filibuster legislation. But in a report made public Tuesday, the nonpartisan Congressional Research Service, Congress' research arm, disagreed with that analysis.
If "a change to the rules were accomplished by a majority vote, nothing would prevent other changes to the rules from being proposed, which could then conceivably be accomplished with a majority vote to end debate on them as well," the research service wrote.
Activists on each side have stepped up their campaigns in the last week. Nearly every day, liberal groups have staged rallies in Washington against what they call a Republican power grab, and several lobbying groups are running television ads around the country.
On the other side, conservative activists held a conference in Washington in which some speakers urged the impeachment of federal judges whose decisions they opposed, including Supreme Court Justice Anthony M. Kennedy.