Immigration and Harry Reid's Clay Pigeon

Go figure.

Only in the arcane world of the U.S. Senate could a quirky gambit known as a "clay pigeon" make the difference between passage of an important immigration measure and its death at the hands of opponents.

Democratic leaders hope the complex manoeuvre, which makes use of the Senate's labyrinthine rules to insist on votes on amendments, will frustrate conservatives' attempts to derail the embattled immigration bill, instead putting it on a fast track to passage next week.

Majority Leader Harry Reid (D-Nev.) said he would revive the bill to legalize as many as 12 million unlawful immigrants late this week. To do so, though, he needs backing from 60 senators, and a way to guarantee votes on a tentative list of 22 Republican and Democratic amendments whose consideration is seen as vital to satisfying key waverers.

The so-called clay pigeon is how he's expected to do it, under a strategy that was still taking shape Monday.

The tactic gets its name from the target used in skeet shooting, which explodes into bits as it is hit. In the Senate, an amendment is the target, and any one senator can demand that it be divided into separate fragments to be voted on piecemeal.

Under the tentative plan, Reid as early as Friday would launch his target - an amendment encompassing all 22 proposals - and shoot it into its component pieces. The Senate would then vote on ending debate on the immigration measure, which would take 60 votes and limit discussion of the bill to 30 more hours. After that interval, all 22 amendments would have to be voted on, with little opportunity for foes to interfere.

Ironically, the move is usually used by mavericks - not leaders - to slow down legislation, not free it from a procedural thicket. Senator Tom Coburn (R-Okla.) used it last year to protest a bill he complained included excessive spending. By offering and then dividing an amendment that targeted 19 items he deemed offensive, Coburn was able to insist on votes on individual projects.

"It's a brilliant way to gum up the works," said Robert Dove, a Senate rules expert who was the chamber's referee for 36 years. The manoeuvre appears to be a relatively modern innovation; Dove said he first became aware of it in the early 1970s, when then-senator Jim Allen (D-Ala.), a master of parliamentary procedures, used it against a bill pushed by the then-majority leader, Senator Mike Mansfield (D-Mont.)

"I remember people being dazzled when he did this," Dove said.

Reid's plan has its risks, chief among them further inflaming the vocal conservative opponents who have vowed to do whatever they can to kill the immigration measure.

"I've seen ideas like this really backfire. You pay a price for this kind of thing," Dove said, noting that the Senate functions almost entirely on consensus. "It can be done - I've seen it done - but it's a difficult manoeuvre. "