WASHINGTON – Behind the stately desk of his Capitol Hill office, the normally agreeable Rep. Jerrold Nadler of Manhattan and Brooklyn suddenly began to fume. “How dare they,” he growled, almost spitting his words, “call my religious tradition a culture of death?”

With that, the six-term congressman charged out the door to deliver the same message on the House floor, where lawmakers were debating legislation to lift restrictions on stem cell research.

The stem cell debate is but one in a recent succession of battles in which Mr. Nadler has found himself on the front lines of the culture wars, perhaps more so than any other House member from New York City.

As a member of the House Judiciary Committee and the senior Democrat on its Constitution subcommittee, he has been at the vortex of recent debates over gay marriage, the Theresa Schiavo case, the Patriot Act, attempts to reduce the jurisdiction of the federal judiciary, and efforts to curtail abortion rights.

And with his approach to stem cell research and his championing of religious liberties issues, Mr. Nadler may be charting a course for Democrats who have recently been accused of opposing “people of faith.”

To Mr. Nadler, the stem cell legislation, which passed the House last week and faces Senate passage – along with a promised veto by President Bush – is not a question of religious versus secular values. Rather, he said, it is a question of respecting a variety of religious values.

As a Jew, Mr. Nadler said he is obliged to support research that could potentially save lives, even if it means destroying human embryos.

“Democrats are not against people of faith,” the 57-year-old Brooklyn native said in a recent interview. They are against “using the power of law to impose religious beliefs as law,” he said.

Mr. Nadler, who attended Crown Heights Yeshiva and graduated from Stuyvesant High School, Columbia University, and Fordham Law School, has castigated lawmakers who argue that killing embryos promotes a “culture of death.” During his speech on the House floor, he said those opponents had been “slandering” other faiths, and the congressman spoke at length about the role of religion in deciding such issues.

“The religious traditions of many of us do not tell us that a 14-day-old blastocyst has the same significance as a human being and do tell us that the obligation to preserve life, which includes the obligation to cure disease and alleviate human suffering, is paramount,” he told his colleagues.

In contrast, Senator Kerry of Massachusetts, for example, issued a statement addressing only the scientific benefits of the research.

Mr. Nadler’s opposition to the “life” agenda has subjected him to some political hardball.

He recently fell under the majority’s wrath for criticizing the Child Interstate Abortion Notification Act – legislation that would make it a crime to transport a teenager across state lines to get an abortion and evade a parental notification requirement in her home state.

Mr. Nadler had some particularly harsh words for the bill – comparing it to the 1850 Fugitive Slave Act, which made it a crime to transport slaves.

That incensed House Republicans, particularly the chairman of the Judiciary Committee, Rep. James Sensenbrenner of Wisconsin, who resented what they saw as a comparison of parents to slave owners.

Mr. Nadler countered that the slave law was the only other instance he could think of where federal law was being used to impose the law of one state on another.

The trouble came after he proposed two amendments to the abortion law. One would have exempted grandparents and siblings from prosecution, and another would have exempted taxicab and bus drivers.

The congressman was shocked when an official committee report described his amendments as an exemption for “sexual predators.” Republicans had reasoned that the grandparents might be sexual predators.

“I’ve never seen anything like this!” said Mr. Nadler of the report, which he described as “libel.” “No one I’ve talked to has ever seen anything like this,” he said, blaming the move on “probably some Nazi on [Sensenbrenner’s] staff.”

Pressure from centrist Republicans eventually led to a change in the description, but Mr. Nadler said the experience left him soured.

“One reason there is such bad feeling in the House now is that extremists are running the show,” he said. “It’s getting worse.”

Despite his complaints about Republican House leaders, Mr. Nadler is supporting a bipartisan effort to overhaul the Patriot Act in light of discomfort in both parties over the law’s expanded police power.

Mr. Nadler, whose district contains ground zero, has recently become co-chairman of the newly formed Patriot Act Reform Caucus, a group of members from both parties who want to change parts of the legislation that was enacted in response to the 2001 terrorist attacks. So far, there are 25 members, nearly half Republican, by his count.

Mr. Nadler, who speaks with machine-gun speed under normal circumstances, fires out a breathless spray of legal analysis when asked to describe the perceived faults in the legislation. “But I wouldn’t say there is nothing good in the Patriot Act,” he concluded of the law, parts of which expire at the end of the year.

Many of Mr. Nadler’s criticisms concern what he believes to be an insufficient role for judges in overseeing the use of the enhanced powers.

And while he does not sit in the Senate, which has a constitutional role in confirming federal judges, Mr. Nadler continuously finds himself defending the independence of the federal judiciary. He is already girding for the political fight over the next Supreme Court nominee.

“It’s bull – ,” Mr. Nadler said of conservative activists and Christian groups pushing for an appointee who would apply a “strict construction” to the Constitution.

“They don’t want strict construction. They want right-wing activists,” he said.

“They want to impose some of the religious-derived notions on the courts. And they want to turn back most of the jurisprudence on economic regulation since 1937.”

From the Schiavo case to the recent battle over Bush nominees to the federal bench, he said, “Everything going on now is just a dress rehearsal for the Supreme Court.”