The Senate’s looming showdown over judicial nominees has lawmakers in both parties nervously eyeing the calendar, as a gambit to squelch filibusters on judges threatens the prospects of passing everything from a massive transportation bill to the most run-of-the-mill post office namings. [IMGCAP(1)]

Amid all the back-and-forth about invoking the “nuclear option” and who’s abusing whom in the Senate, the real victim will likely be the legislation — that is, if Senate Majority Leader Bill Frist (R-Tenn.) follows through on his threat to force an end to the Democrats’ filibustering ways and Democrats follow through on their vow to bring Senate action to a virtual standstill.

Indeed, the notion that eliminating filibusters on judges could lead to much wider use of the same tactic on legislation has been on the minds of Senators of both parties as they contemplate just what won’t get done in the 109th Congress.

“It affects everything … especially since [the Democrats’ threatened blockade] will be more or less along procedural lines rather than against specific legislation,” said an aide to Senate Judiciary Chairman Arlen Specter (R-Pa.).

As early as next week, Frist could decide to invoke the nuclear option (or as Republicans now like to call it, the “constitutional option”) by forcing a ruling from the Senate’s presiding officer that filibusters are unconstitutional. Any such action would only need 51 votes to succeed, as opposed to the 60 needed to break a filibuster.

Senate Minority Leader Harry Reid (D-Nev.) has refused to say which pieces of legislation would be impacted by a Senate slow-down, but has noted that legislation for American troops in action in Iraq and Afghanistan and measures affecting critical government services would not be impacted.

“I can’t get into specifics,” said Reid spokesman Jim Manley. “The Republicans will know the difference between a cooperative minority and an uncooperative minority. … If Sen. Frist decides to break the rules, Democrats will ensure that the rules are enforced to the extent possible in order to stop a further partisan power grab by Republicans.”

Bills to reshape the nation’s energy policy, overhaul Social Security, revise immigration laws, insulate gun manufacturers from litigation, shield doctors from malpractice lawsuits and protect unborn fetuses could all either be blocked or slowed down significantly.

In a letter to Reid, Senate Majority Whip Mitch McConnell (R-Ky.) implored the Democratic leader to drop both his threats to shut down the Senate and his insistence on filibustering 10 judicial nominees so that the Senate could move forward with exactly those types of bills.

“This Senate needs to enact a long-term energy policy to reduce our dependence on foreign oil. In addition, our transportation infrastructure needs improving. … It is critical that the Senate pass a highway bill. We also must reform America’s tax code so that it is fairer for all Americans,” McConnell said Monday. “I urge you to work with the Majority Leader to repair our broken judicial confirmation process.”

Of course, some of the those bills — such as a future Social Security bill and the medical malpractice measure — might be filibustered regardless of whether either party goes “nuclear.”

So it’s anybody’s guess which bills could be held up simply because Democrats start tapping the brakes in the already slow-moving Senate. Arcane procedural maneuvers available to Democrats can ensure that whatever does happen, doesn’t happen quickly. And if they all stick together, Democrats can prevent bills from passing by using the traditional, non-judicial filibuster, which presumably will not have been ruled unconstitutional by the Senate’s presiding officer.

Republicans have likened the Democrats’ threatened tactics to the 1995 government shutdown that was widely pinned on Republicans and caused the GOP to lose significant ground in the 1996 elections.

“I am greatly concerned about your statement regarding shutting down Senate business, and by extension, the federal government,” McConnell wrote in his letter to Reid.

But Democrats dispute that notion.

“There was never any attempt to shut down the government,” said Manley. “Republicans will be the ones to shut down the Senate with their radical, unprecedented maneuver.”

Regardless of who might be at fault, the biggest losers could be those Senators seeking to honor a local politician with a Post Office or court house naming bill and others pushing bills with largely noncontroversial parochial interests in mind. Those types of measures typically gain unanimous consent for passage as the Senate wraps up its business every evening.

For example, the Senate last week passed a measure naming a federal courthouse in Sacramento, Calif., after the late Rep. Robert Matsui (D-Calif.) as well as a bill to extend a law on leaking underground storage tanks.

Democrats could have forced days of debate and seemingly endless votes on each of those issues, but if Frist moves forward with the “constitutional option,” it’s likely those bills will never see the light of day.

“We’d probably still try to do wrap-up, but if [Democrats] objected, we couldn’t do it,” said Frist spokeswoman Amy Call.

Similarly, even presidential nominations to low-profile posts such as the Federal Housing Finance Board or the IRS Oversight Board might have to be put up for debate and voted on.

So if small issues like court house names and minor nominations could take a week or more to debate, imagine the impact the Democratic threat to “enforce the rules” could have on bigger, more contentious pieces of legislation.

For example, Specter is in the final days of negotiating a long-awaited deal on a bill to compensate victims of asbestos exposure. Specter is “hopeful” that his compromise legislation can be introduced this week and possibly marked up by committee next week, said the Specter aide.

Still, that timeline could change if Frist actually chooses to make the nuclear move next week.

Indeed, committee markups, like the one tentatively planned for the asbestos bill, could also drag on for days or weeks if Democrats use a little known rule to prevent committees from meeting once the Senate has been in session for two hours. Plus, by knowing which Republicans might be out of town or out of pocket at any given time, Democrats could deny Specter or other Republican committee chairmen the needed quorum for marking up legislation.

As a rule, most committees only need all of their GOP members to show up to constitute a quorum if no Democrats are present. As an unofficial rule, many Senate committees already have a problem with maintaining a quorum given that Members of both parties routinely skip markups in order to attend to other obligations.

In addition to the asbestos bill, the Judiciary panel’s consideration of a reauthorization of the PATRIOT Act and a potential bill to shore up court house security could be affected, the Specter aide said.

Meanwhile, Reid, whose threatened actions would create the legislative stalemate, appears to be trying his mightiest to get Frist to bring up the highway funding bill before anyone drops the filibuster bomb.

Reid and a handful of interested Democratic colleagues wrote a letter to Frist last Thursday imploring him to bring up the highway bill “prior to the completion of this April work period.” Given that this week will be eaten up with the Senate’s continuing consideration of an $80.6 billion supplemental war-spending bill, that only leaves next week for consideration of highways — a bill in which just about every Member of Congress has a stake.

Coincidence that Reid wants to supplant going nuclear with the highway bill? His office won’t say.

But the highway bill isn’t the only fish that might get fried by the radioactive fallout of the nuclear option. Consider, for example, the reauthorization of the 1996 “Welfare to Work” bill, which forced states to move more people off public assistance and into jobs.

Sen. Olympia Snowe (R-Maine) worked long and hard to get extra funding for childcare into the welfare bill this year. But even though the welfare bill has been ready for floor action for more than a month, Senate Budget Chairman Judd Gregg (R-N.H.) has reportedly been loathe to bring up the measure until he gets a bicameral agreement on a budget resolution.

In any event, Snowe is concerned that the welfare bill might also become a victim of the nuclear option.

“Given that the budget and the nuclear option are looming large in the Senate, we hope that neither of those [two actions] would serve to block welfare from coming to the floor,” said Antonia Ferrier, spokeswoman for Snowe. Indeed, Ferrier said, “There are lots of pieces of legislation we’re worried about.”

Because the welfare bill has a good deal of bipartisan support, Ferrier said Snowe hopes Democrats might give it a pass.

But as Reid’s Manley said, “We have to preserve all of our options. … We’ll take things on a bill-by-bill basis.”