WASHINGTON – Senator Schumer yesterday labeled the head of the conservative Christian Family Research Council “un-American” for accusing Democrats of using the filibuster to block religious judicial nominees.

The accusation came as the Senate majority leader, William Frist of Tennessee, plans to make a speech to a conference organized by the group Sunday. The nationally televised event will argue for an end to the Democrats’ ability to use filibusters to delay judicial nominations in the Senate.

A flier for the event states that “the filibuster was once abused to protect racial bias, and now it is being used against people of faith.”

Dr. Frist is under pressure to persuade his colleagues to reduce the number of votes required to end a Senate filibuster of judicial confirmations from 60 to 41.

Several federal judicial nominees whom Democrats oppose hold strong Christian beliefs, but Mr. Schumer said their nominations are being blocked for unrelated reasons – including their views on the limits of congressional power relative to the states and their opposition to some environmental regulations.

The conservative group’s president, Tony Perkins, “stepped over the line,” Mr. Schumer said. “He said it’s people of faith versus Democrats.”

“That is so un-American. The founding fathers put down their plows and took up muskets to combat views like that – that one faith or one view of faith should determine what our politics should be,” Mr. Schumer said on the ABC News program “This Week.”

Senator Clinton had no comment yesterday. Dr. Frist is expected to provide a videotaped speech that will be broadcast as part of the conference telecast. The Senate minority leader, Harry Reid of Nevada, has also condemned Dr. Frist.

“Participating in something designed to incite divisiveness and encourage contention is unacceptable,” he said.

“This is a democracy, not a theocracy,” Mr. Reid added.

Senator Feinstein, a Democrat of California, said senators who had opposed the nomination of a Catholic judge were called “anti-Catholic,” a label she called “chilling.”

“I think it’s a very dangerous, extreme thing. I think there is no telling what it might launch. It’s entirely false,” she said of the Family Research Council’s message.

A spokesman for Dr. Frist, Bob Stevenson, has accused Democrats of a “clear double standard” because they did not criticize Senator Kerry last October when he denounced President Bush in a speech at a Baptist church in Florida.

Several Republicans also publicly criticized the message, although they stopped short of directly chiding Dr. Frist.

“We have to be very careful here,” said Senator Hagel, a Republican of Nebraska.

“I see drifting here in different directions that I don’t think are healthy for our country. … Neither religion nor government should become an instrument for the other,” he added.

Senator Graham, a Republican of South Carolina, criticized the Family Research Council’s message in an interview with Newsweek magazine, “Questioning a senator’s motives in that way is a very dangerous precedent. That goes to a level where the Senate has never gone before. It is a very unhealthy turn of events,” he said.

Both Messrs. Hagel and Graham are considering running for the Republican presidential nomination in 2008. Mr. Frist is also a likely contender who is expected to seek support from the religious conservative base of the party.

A conservative commentator, George Will, took issue with Mr. Schumer’s remarks yesterday, noting that Democrats have historically welcomed preachers into their politics.

“The question of whether he crossed the line presupposes there is a line. I don’t know what they are talking about,” Mr. Will said.

“When the religious involvement in politics was primarily the Reverend Martin Luther King, the Reverend Ralph David Abernathy, the Reverend Jesse Jackson, and the Reverend William Sloane Coffin, this was considered a healthy leavening of our democracy by faith. Now when Republicans do it, there is a line somewhere,” he said on “This Week.”

In a letter to supporters, Mr. Perkins wrote, “For years activist courts, aided by liberal interest groups like the ACLU, have been quietly working under the veil of the judiciary, like thieves in the night, to rob us of our Christian heritage and our religious freedoms.”

Many nominees “are being blocked because they are people of faith and moral conviction,” he wrote. If the filibuster is not stopped, “the best we can hope for are likely to be mediocre judges who meet the approval of Ted Kennedy, Charles Schumer, and Hillary Rodham Clinton.”

Television commentator Cokie Roberts questioned the mention of Mr. Schumer, despite his leading role among Democrats in Senate judicial politics.

Citing Mrs. Clinton and Mr. Kennedy is expected, because they are “bugaboos of the right,” she said. “Then they throw in Chuck Schumer, you start to think they were looking for a Jewish name, and I think that is a real problem,” Ms. Roberts said.

A former aide for judicial nomination issues to Dr. Frist, Manuel Miranda, distributed talking points to Republicans yesterday, arguing that the “the abortion litmus test is nothing but a surrogate for a constitutionally prohibited religious test.”

Democrats have denied applying such a test, and stress that they have confirmed numerous pro-life judges.

Article Six of the Constitution states, “No religious test shall ever be required as a Qualification to any Office or public trust under the United States.”

The chances of the anti-filibuster bill passing the Senate grew stronger yesterday as one hitherto recalcitrant Republican senator said he is likely to side with the party leadership on the issue.

Senator Lugar, a Republican of Indiana, said he hoped the impasse over judges could be resolved through negotiation, but that he would vote to end the filibuster “if push came to shove,” he told “Fox News Sunday.”

Meanwhile, Mr. Hagel said he remained undecided.

“I do not like this approach. It’s a dangerous approach and it’s an irresponsible approach, and it further erodes the constitutional minority rights in the Senate,” he said of the proposal.