The Democratic holdouts are believed to be Sen. Carl Levin (MI), an outspoken opponent of a partisan rules change, and Sens. Mark Pryor (AR) and Max Baucus (MT).
Despite threatening to change the rules with 51 votes two years ago, and again last winter, Democrats conceded after the bipartisan rules change in January that they never had the votes to go nuclear. This time they say they are more fed up with needless delays and blockades, and are prepared to narrowly scrap the filibuster for executive nominations. But Democrats privately concede they don't have the votes to weaken the filibuster for legislation or judicial nominees.
During a Monday speech at the Center for American Progress, Reid made an unequivocal ultimatum to Republicans: Confirm the seven pending nominees or we'll move forward and change the rules on a simple majority vote.
"The status quo won't work," he said, calling the GOP's obstruction "unbelievable" and "untoward." He said Republicans must "either allow these people to go through -- that is, stop the filibuster, or where gonna have to change the rules."
While Reid has lost his patience with the Senate GOP's use of the filibuster to slow down and delay executive nominees, his threat is largely about Republican efforts to refuse to confirm anyone to lead two agencies they disapprove of: the National Labor Relations Board and Consumer Financial Protection Bureau.
It's the Democrats' three NLRB nominees and Richard Cordray for the CFPB whom the battle is likely to come down to. Other nominees -- including Gina McCarthy to lead the Environmental Protection Agency, Tom Perez for the Labor Department and Fred Hochberg for the Export-Import Bank -- are likely to be confirmed, Republicans concede.
"There isn't, as I've indicated, a single objection to the qualifications for any one of these people," Reid said. "And we need to move forward. We need to stop blocking this president and the future presidents from having a qualified team that he thinks is what he needs."
Procedural votes on all seven nominees will begin on Tuesday.
White House spokesman Jay Carney told reporters Monday that President Obama "supports Harry Reid" if he decides to move forward with a rules change and "believes the Senate ought to function."
Of the ongoing GOP filibusters, Carney said, "This has become ridiculous."
Reid made clear that he has no intention of scrapping the filibuster when it comes to legislation or judges. He cited a variety of examples in recent decades when the majority leader has changed Senate rules and procedures by a simple majority vote.
Senators are scheduled to discuss the issue at 6 p.m. ET on Monday during an all-members meeting. Senate Minority Leader Mitch McConnell (R-KY) has aggressively warned Reid not to move forward with the rules change, arguing that every one of President Obama's nominees this year have eventually been confirmed. He said he hopes that "cooler heads will prevail" after the Monday meeting, promising retribution if Democrats pull the nuclear trigger.
"I hope we'll come to our senses and not change the core of the Senate," McConnell said Sunday on NBC's "Meet The Press." "We have never changed the rules of the Senate by breaking the rules of Senate in order to diminish the voices of individual senators."