WASHINGTON -- Senate Majority Leader Harry Reid moved closer Thursday to dramatically altering Senate rules in order to block the chamber’s Republican minority from filibustering President Barack Obama’s executive nominees.

Senate business ground to a halt Thursday morning as Reid, D-Nev., ending weeks of silence on the filibuster, set the stage for a confrontation between Democrats and Republicans when he accused Senate Minority Leader Mitch McConnell, R-Ky., of breaking an agreement the two forged last January aimed at easing complaints about Republican obstruction of nominees.

“He has failed to do what he said he would do, move nominations by regular order except in extraordinary circumstances,” Reid said in a sometimes-tense exchange with McConnell on the Senate floor. “I refuse to unilaterally surrender my right to respond to this breach of faith. I wait, I wait, but I’m not going to wait another month, another few weeks, another year for Congress to take action on the things that we have been doing for 200 and almost 40 years.”

He upped the ante by moving for votes on seven nominees, including Richard Cordray as the director of the Consumer Financial Protection Bureau, Gina McCarthy to lead the Environmental Protection Agency, Thomas Perez for secretary of labor and the nominations of three National Labor Relations Board members whose recess appointments were ruled unconstitutional by the federal courts.

Reid’s actions laid the groundwork for him to invoke the so-called “nuclear option,” which, by Senate vote, essentially would end filibusters by preventing Republicans from requiring a 60-vote super-majority for confirmation of Cabinet-level and executive branch nominees. Instead, the Senate would confirm nominees by a simple majority vote.

Democrats control 54 out of 100 votes in the Senate, plus they have the steady support of two independents.

“My friend the majority leader is going to be remembered as the worst leader in the Senate ever,” McConnell said. “It makes me sad.”

McConnell and other Republican senators said the current Senate rules had worked just fine, with all of Obama’s Cabinet nominees confirmed and many of his executive picks in the process of being confirmed. McConnell accused Reid and other Democratic senators of “manufacturing a pretext for a power grab,” in part to ramrod National Labor Relations Board nominees through the Senate.

“So let me sum up what’s going on here,” McConnell said. “Senate Democrats are getting ready to do permanent damage to this body, to confirm three unconstitutionally appointed nominees by a simple majority vote. . . . Every other nomination we’re talking about here has either been confirmed or is on the way to being confirmed.”

Reid countered that his flirtation with the nuclear option was born of frustration over what he considers McConnell’s backtracking on the January agreement and the filibuster of the eventually successful nomination of former Sen. Chuck Hagel, R-Neb., to be defense secretary. Hagel was the first-ever defense nominee to be filibustered.

The Senate confirmed 24,296 nominees last year, up from 19,815 in 2011, according to figures provided by the chamber. The 2012 numbers are roughly in line with confirmation numbers from 1997, the first year of President Bill Clinton’s second term, to 2010.

The Reid-McConnell showdown on the Senate floor sent lawmakers scurrying into separate lunch meetings, with Democrats weighing whether they had the votes to employ the nuclear option and Republicans caucusing about what to do if Reid pushes the button.

“We find ourselves in the situation of a tyranny of the minority,” said Sen. Tom Udall of New Mexico, one of a handful of Democrats who’ve been working to revamp filibuster rules. “The founders saw that if you created a situation where the minority could block the action of the Senate, then the minority would actually be governing. And that’s the situation we have before us today.”

Sen. Pat Roberts, R-Kan., warned that if the nuclear option were successful, the Senate would move away from its traditional advise and consent role and become more like the House of Representatives, where the majority party strongly dominates the minority

“This is just not a minor shot across the bow to be used only once,” Roberts said. “This is a mushroom cloud over the Capitol. Again, I would urge the distinguished majority leader: Don’t take your nuclear gun to town.”

A bipartisan group of senators will meet Monday in the old Senate chamber in hopes of finding a compromise.