Rep. Jerry Nadler insists it isn't political, but lately he's been on a tear against Bush administration officials — whether concerning environmental neglect at Ground Zero or if federal officials acted on credible terrorist threats before the Sept. 11 attacks.

"We need a clear investigation," Nadler, D-N.Y., told Fox News.

"If you had vague rumblings that bin Laden was out there and didn't like us and was plotting to hurt us, there was nothing the president could really do," he said. "But if there was evidence that there might be a plane hijacking, and the administration didn't tell the airlines to beef up security, then we have a problem."

After the contents of the administration's August briefings hit the news cycle last Thursday, Nadler hit the TV talk show circuit, where his language was more strident. In one case, he said if hearings proved that the Bush administration had prior knowledge of the attacks and it failed to act, it would be akin to "malfeasance of the highest order."

And Nadler's not afraid to speak up on matters other than national security. Earlier in the week, he called upon the Republican National Committee to give to charity the money raised from the sale of publicity photos depicting President Bush speaking via cell phone on Air Force One with Vice President Dick Cheney hours after the World Trade Center and Pentagon attacks. He said the money should go to the families of the victims.

"I ask you in the spirit of unity and bipartisanship which arose after the horrific events of Sept. 11 to donate the receipts from the sale of this photo," he said in a letter sent to Cheney and others.

But some question whether the New York City congressman has a bipartisan bone in his body.

"He's clearly a partisan attack dog," said Carl Forti, a spokesman for the Republican National Campaign Committee, adding that Nadler has never seen a defense or intelligence budget he didn't want to cut. "He's a hypocrite."

"Anything he does is about politics and negative attack politics," said Patrick McCarthy, a spokesman for the New York Republican State Committee. "He's a highly partisan individual — even for New York."

Certainly the four-term representative has been called worse. A staunch liberal who does not mince words over what he believes, he drew national attention in 1998 when he emerged as one of the Democratic pit bulls defending then-President Clinton against impeachment.

Calling the obstruction of justice charges against Clinton, who was impeached by the House, a "partisan coup d'etat," Nadler was active in trying to disarm his Republican colleagues on the House Judiciary Committee with legal questions, quips and his own flippant attacks. At night, he would argue his case on the television talk shows.

Looking back on it today, he wouldn't change a thing, he said.

"The whole thing was a put-up job," said Nadler, who admitted he was never a big fan of Clinton. "It was a perjury trap and it was all done to trap the president."

To Democratic colleagues and friends, Nadler is far from a knee-jerk liberal, but a feisty lawmaker who spends an extraordinary amount of time doing his homework. He's well-liked in his liberal, heavily Jewish district, much of which sits in the heart of the World Trade Center rubble and across the affluent, hip areas along the Upper West Side, Chelsea, Greenwich Village, SoHo, and parts of Brooklyn.

"His approach to political issues is a very scholarly, very focused, very thorough — some would even say plodding approach," said Dick Morris, former Clinton adviser and old college roommate of Nadler's. The two had been working on political campaigns in one form or another since their years at Stuyvesant High School in Manhattan in the 1960s.

"He's very liberal — and he has to be in the district he's in — but he's not someone whose liberalism is reflexive," said Morris.

Members of the New York delegation say Nadler, who is so far running unopposed in this year's re-election, proved his loyalty to the district after Sept. 11, especially when it came to acquiring business loans for small businesses affected by the attacks.

"He's been amazing since Sept. 11," said Rep. Anthony Weiner, D-N.Y., whose Brooklyn district abuts Nadler's. "He's cajoled, compromised and rattled cages" to get the needs of his people met, he added.

Nadler continues to be a thorn in the side of the Environmental Protection Agency over what he called neglectful assessments and follow-up to indoor and outdoor pollution levels in the Ground Zero area post-Sept. 11.

Last week, after months of his public attacks on EPA Administrator Christine Todd Whitman and her staff, the agency said it would begin to fund the asbestos cleanup of individual homes around Ground Zero as requested by homeowners.

"It was a great step forward," he said, but not the end of his crusade.