War protester Cindy Sheehan came to New York last night with a blunt warning for Senator Clinton: End your support for the war in Iraq or else.

Visiting New York City for the first time since leaving her campsite outside President Bush’s vacation ranch in Crawford, Texas, Ms. Sheehan told a packed audience in a Brooklyn church that Mrs. Clinton “knows the war is a lie” but because of her political ambitions refuses to voice any opposition.

Mrs. Clinton is “waiting for the best political moment to say” she opposes the war, Ms. Sheehan said during a 15-minute speech. “You say it or you’re losing your job,” she said, provoking a roar of approval from the audience. Mrs. Clinton, believed to be a possible presidential contender in 2008, has said she supports the war in Iraq and has pushed for a greater troop presence in the country.

In an interview after her speech, Ms. Sheehan said she has requested a meeting with Mrs. Clinton but has not gotten a reply. Mrs. Clinton’s office was not immediately available for comment last night.

Ms. Sheehan, who has demanded a second face-to-face meeting with Mr. Bush to discuss the war, suggested that there was little the president could say at this point to appease her. She called his administration “reckless” and “insane” and said “maniacs” are running America.

She also seemed to broaden her stance against America’s military presence in Iraq to an opposition to war in general, saying, “We want to make sure it never happens again.” She said she was motivated not just by the grief caused by the death of her 24-year-old son Casey, a soldier killed in Baghdad in April 2004, but by an effort to save the world’s children.

“The children of the world are not safe,” she said. “We have to do it for them.”

She also criticized the press for picking on her and said it has corrupt motives in its coverage. “If you look at who owns most of the mainstream media, they all profit off of this war. We have to stop making war profitable.”

Ms. Sheehan spoke to about 300 people inside the sanctuary of the Civil War-era Lafayette Avenue Presbyterian Church, located on the corner of South Oxford Street and Lafayette Avenue in the heart of the Fort Greene neighborhood. The audience was a mixture of Brooklyn residents, anti-war protesters, and a handful of politicians, including City Council members David Yassky and Letitia James. Also in the audience was television personality Phil Donahue, who said he was “very, very impressed with this woman’s courage.” In an interview outside the sanctuary, he described Ms. Sheehan as a “lightening rod of an important effort to stop this immoral war.” The reverend of the church, David Dyson, called Ms. Sheehan “one of the bravest women in the United States of America.”

Arriving more than an hour late apparently because of traffic and bad directions, Ms. Sheehan stepped out of a white recreation vehicle and entered the church. An ecstatic audience had risen to its feet. As the Lafayette Inspirational Ensemble chanted “Ain’t gonna study war no more,” Ms. Sheehan sat down, crossed her legs, and slowly nodded to the choral music.

Ms. Sheehan’s month-long vigil outside Mr. Bush’s vacation ranch propelled her to the national stage as the symbolic face of an anti-war movement that had lost some of its force. Thousands of opponents of the war joined her at her “Camp Casey” in Texas, as did a large contingent of pro-war demonstrators who staged rallies in support of the Bush administration. As a grieving mother seeking answers, Ms. Sheehan has won sympathy from Americans who have reservations about Mr. Bush’s handling of the war, but she has also alienated others, including families of other American soldiers killed in Iraq, who say a partisan political agenda has corrupted her message.

While her protest began as a simple demand to meet with the president, her criticisms of Mr. Bush have expanded beyond foreign policy. After touring parts of Louisiana last week, Ms. Sheehan wrote a letter posted on filmmaker Michael Moore’s Web site in which she accused the federal government of evacuating people unnecessarily in the days after Hurricane Katrina struck the Gulf Coast. “George Bush needs to stop talking, admit the mistakes of his all around failed administration, pull our troops out of occupied New Orleans and Iraq, and excuse his self from power,” she wrote.

Ms. Sheehan is to speak today at St. John the Divine in Manhattan, with much larger crowds expected to attend. Organized in part by the anti-war group United for Peace and Justice, her stop in New York is part of what is billed as “The Bring Them Home Now Tour,” which concludes on September 21 when three buses traveling along regional routes converge in Washington, D.C., three days before an anti-war rally on the National Mall. Ms. Sheehan has said she plans to set up a vigil near the White House that will resemble the Crawford campsite.