This really isn’t complicated. If Republicans don’t want Democrats to exercise the nuclear option and do away with the filibuster on executive branch and judicial nominations by a simple majority vote, as Harry Reid has been threatening to do, all they have to do is drop the endless, unprecedented obstruction of those nominations.

Scholar Norman Ornstein has been a close observer of Congress for decades. Recently he published a book arguing that in today’s GOP, we’re seeing a level of obstructionism — and an undisguised devotion to fomenting government dysfunction for purely partisan ends — that is radical and unprecedented. Though Republicans screamed about this judgment, Ornstein did not reach it lightly, and his book backs it up in meticulous detail.

Today Ornstein weighs in with another piece on the current battle over the filibuster. This battle is escalating on two fronts: Over Obama’s choices for three key executive branch positions, and over his plan to fill three vacancies on the D.C. Circuit Court of Appeals, a key ideological battleground.

Ornstein actually bends over backwards to be fair to Republicans, noting that Dems strongly opposed the nuclear option when Republicans threatened it amid Dem obstructionism of George W. Bush’s judicial nominations. But Ornstein points out that things are far worse — again, unprecedented — today. And he asks a key question: Where are the moderate Republican Senators who know full well that what Mitch McConnell is doing is indefensible, and that it will leave Dems no choice but to hit the nuke button if it continues? Ornstein:

I remain deeply uneasy about a nuclear option, even as I condemn the unprecedented obstructionist tactics employed in the Senate (which were also condemned last week by Bob Dole and lamented by John McCain) and call for deeper reforms, especially on nominations, in Senate rules. The fallout from such a move is unknown but would be substantial and deleterious.  It would be far better to return to regular order, and to the use of filibusters as rare events, not routine ones.

But if senators who know better — like Lamar Alexander, Bob Corker, Susan Collins, Lindsey Graham, and Saxby Chambliss — jump when McConnell tells them and continue to obstruct nominations, they should expect to reap the whirlwind. And they, and their colleagues, will be the ones responsible for the damage done.

Look, the basic situation here is that Democratic leaders don’t want to hit the nuke button. This should be painfully obvious to anyone who’s paying even cursory attention to what’s happening. Harry Reid could not muster 51 votes for rules reform at the beginning of the year, because veteran Dem Senators were uncomfortable changing the rules by simple majority. Hence, the watered down bipartisan filibuster reform compromise. This resistance remains today — indeed, this is something that frustrates liberal reformers to no end — though it is weakening.

But if the current levels of obstructionism continue, Reid and fellow Democrats will have no choice but to go through with hitting the nuke button, even against their own will. The pressure on them from key Dem constituencies who have a major stake in seeing those executive branch and judicial nominations go forward — labor, environmentalists, etc. — will be very intense. At a certain point, not challenging GOP efforts to prevent the government from function on a basic level will be a completely untenable position with regards to the Democratic base.

Republicans are likely to play a very dangerous game as this continues to unfold. They will probably allow the minimum of nominations to slip through, gambling that Reid doesn’t have the guts — or the support from fellow Dems — to go through with rules reform. Perhaps they are right. But the escalation on two fronts makes miscalculation on their part more likely. As David Firestone points out, whatever Reid’s resolve, one thing he does know is that the current situation can’t hold.

Ornstein is right: Where are the moderate Republican Senators who know full well that all of the above is the case, and know full well that the current level obstructionism is indefensible?

This is on Republicans. If Dems end up hitting the nuke button, Republicans will be to blame for it.