Many take with a large grain of salt the grandstanding that's become common in the partisan Congress, with one side squawking that the other threatens the very fabric of America ... over differences that can seem laughably small once the smoke clears away.

But while such cynicism is understandable, the skepticism voiced by Republican Sen. Arlen Specter about the administration's breezy defense of its ongoing, warrantless domestic spying campaign is worth a closer look.

In response to written questions from Sen. Specter, who chairs the Senate Judiciary Committee, Attorney General Alberto Gonzales replies the spy program is not "a dragnet that sucks in all conversations and uses computer searches to pick out calls of interest."

But in light of Sunday's reporting in The Washington Post, Sen. Specter calls that response "strained and unrealistic."

Indeed, to argue the system does not monitor "all" calls would seem to employ the "straw man" technique of denying something that no one has alleged.

What The Post reported Sunday is that -- while the Bush administration refuses to say how many Americans have had their overseas calls recorded or their e-mails read by intelligence analysts without court authority -- "knowledgeable sources" place the number as high as 5,000.

President Bush defended the program in his State of the Union speech last week, saying, "If you're talkin' to a member of al-Qaida, we want to know why."

But the vast majority of calls subject to the warrantless eavesdropping are quickly dismissed as unrelated to any terrorist, The Post reports -- fewer than 10 U.S. citizens or residents per year arouse enough suspicion during warrantless eavesdropping to justify a warrant for further investigation.

That sounds an awful lot like "using computer searches to pick out calls of interest" -- and certainly explains why the administration might rebel at even the most minimal demands to show "reasonable cause" for snooping on individuals.

National security lawyers, both in and out of government, tell The Post the high proportion of innocent bystanders whose calls are monitored, but who are then "washed out" as suspects, "raised fresh doubt about the program's lawfulness under the Fourth Amendment because a search cannot be judged 'reasonable' if it based on evidence that experience shows to be unreliable."

The Congress in 1978 set up a special, secret court where the administration can go to get quick warrants in national security cases. Sen. Specter says the courts set up by the Foreign Intelligence Surveillance Act "has really an outstanding record of not leaking, and of being experts. And they would be pre-eminently well qualified to evaluate this program and either say it's OK or it's not OK."

So why has the president been bypassing the FISA court? If the FISA law is inadequate, the president should have asked that it be amended, rather than simply ignoring it, Sen. Specter says.

Since that identifies the bright line between a republic based on law, and a high-handed proto-dictatorship, let's identify Sen. Specter's remark as a massive understatement.

As for claiming a general 2001 congressional authorization to use force in fighting terrorism OK'd this end run around the law, "The authorization for the use of force doesn't say anything about electronic surveillance," Sen. Specter responds.

Arlen Specter is a prominent member of the president's own party. He will turn 76 next week, and is not a presidential hopeful. His challenge cannot easily be dismissed as partisan sniping or posturing for political advantage. And even if one credits Mr. Bush and his administration with the best of intentions, once such a precedent is tolerated, does anyone doubt future administrations might broaden such snooping, justifying such efforts as a search for drug dealers, child molesters, "deadbeat dads," or whatever?

Both Sen. Specter and ranking committee Democrat Sen. Patrick Leahy of Vermont say the committee will resort to subpoenas if they do not receive more detailed answers.

Good. The senators cannot allow this issue to be swept under the rug.