An important moment on the Senate floor just now: Harry Reid said he would be filing cloture today on a whole bunch of executive nominations, and challenged Republicans to act on them — a major escalation of the threat to change the Senate rules by simple majority, i.e, the “nuclear option.”

“We’re going to file cloture on a bunch of nominations, and those votes will occur next week when we schedule them,” Reid said, adding later that if no movement occurred on them, “we know what’s going to happen.”

According to a senior Senate Democratic aide, this means that Reid will file cloture on the following nominations today: Richard Cordray as head of the Consumer Financial Protection Bureau; Gina McCarthy as head of the Environmental Protection Agency;  Obama’s picks to the National Labor Relations Board; and possibly Thomas Perez as Labor Secretary.

What this amounts to, really, is an effort to reshape the Democrats’ strategy as they head into a lunch today to determine whether they will exercise the nuclear option. Here’s my read on how you can expect things to unfold:

1) Reid will tell Democrats at his caucus lunch today that the decision on whether they change the rules via simple majority — eliminating the filibuster on executive nominations — should turn on how Republicans respond to the above nominations early next week.

2) Reid will take the temperature of the Democratic caucus on rules reform, and see whether there is majority appetite for a rules change.

3) Reid will file cloture on all of the aforementioned negotiations later today.

4) Democrats will privately continue to discuss the situation as the Republicans respond to those nominations.

5) Next week, depending on how Republicans respond, the final decision on whether to go nuclear will be made.

In a sense, what this move does is that it shifts the debate over rules reform back onto Republicans. While it remains unclear whether Reid has the support of 51 Dems to change the rules,  this is in effect a message to Democrats that they can base their decision on whether to go nuclear on Republican conduct, on how Republicans respond to the Cordray, NLRB, EPA, and Labor Secretary picks. Even if there remains resistance among Dems to going nuclear, this will give them a framework within which to make the final decision.

In other words, Reid’s move today is as much about giving Dems a way to take the nuclear plunge, if necessary, as it is about drawing a very clear marker on what Republicans must do in order to avoid nuclear Armageddon.

In short, Reid is dramatizing the stakes here for Dems in his own caucus as well as for Republicans. On the Senate floor today, Mitch McConnell signaled that McCarthy and Perez would be allowed to move forward, but it remains unclear when, and it’s still unclear whether Republicans will lift their blockade on Cordray — whom Republicans are holding up simply because they want to prevent the CFPB from functioning — or on the NLRB nominations.

By filing cloture on all of them, Reid is giving Republicans one last chance to move on them, on the theory that if they fail to do so, it will help drive home to fellow Dems — and the media, and the American people — that they really have no choice but to hit the nuke button.

Greg Sargent writes The Plum Line blog, a reported opinion blog with a liberal slant -- what you might call “opinionated reporting” from the left.