The Democrats made a forceful move this morning to defeat the first Republican effort to cripple the immigration overhaul. Majority Leader Harry Reid, D-Nev., opened the third day of proceedings by moving to table, and thereby kill, the opening GOP bid for bolstering the bill’s border security provisions.

The amendment was designed to impose such a high threshold for border security that the “gang of eight” coalition behind the underlying bill would fracture. But Reid’s maneuver to kill it without so much as a fare thee well also threatens to upend the rickety bipartisan agreement to stay on course for a textbook friendly debate.

Reid’s move infuriated opponents of the bill, who said their right to keep talking while they worked to build a coalition for their proposal had been stripped away without fair warning.

“This so-called open and fair process is a farce,” the top Judiciary Committee Republican, Charles E. Grassley, called out just before the roll call. “This is a very provocative act.”

Grassley wrote the amendment at issue, which would require the Department of Homeland Security to certify that the Mexican border had been fully secured for six full months before the bill’s new system could begin to legalize people now in the country illegally. Critics said that requirement would be an additional and impractical burden on the already-arduous path toward citizenship at the heart of the measure.

Reid’s move needed only 50 votes to succeed; he got 57.

As reported on Roll Call’s #WGDB blog, the majority leader’s parliamentary tactic was a quick rejoinder to the bill’s opponents. They had complained bitterly on Wednesday that their efforts to hobble the legislation were being subjected to an unfairly high 60-vote threshold for success. But they shouldn’t have been surprised, since such supermajorities have become the increasing norm in the Senate in recent years as the only way to avoid time-consuming filibusters by whichever caucus is on the losing side of a proposal.

For Reid, the power to call for tabling motions gives him additional leverage to move the debate along at a relatively brisk pace — and with solid odds of keeping the bill to his liking. He can make ideas he views as poison pills go away with 51 votes, while the other side will need 60 votes to add language viewed as killer amendments by the Obama administration, the gang of eight and the coalition of business and labor groups pushing the measure.

As a scheduling matter, applying such muscle is probably the only way the final roll call on passage can be called by two weeks from tomorrow, the day senators are supposed to be dispatched for their July Fourth recess.

To that end, Reid announced after this morning’s vote that senators should plan to stay in town the weekend of June 22 and 23 for votes on the bill. He then declared that work on the immigration measure was over for this week.