James Stewart filibustering in "Mr. Smith Goes to Washington."

Democrats are regretting their decision to invoke the “nuclear option” – to weaken Senate filibuster rules so that those pesky Republicans couldn’t slow President Barack Obama’s agenda.

Now that President-elect Donald Trump is coming into power, the Democrats say those rules are needed once again. They manage to do so without actually admitting they made a mistake.

One Senate Democratic leader, Sen. Chris Coons of Delaware, puts it this way: He’s sorry they made him do it.

“What I regretted was that then-Minority Leader McConnell so overused the filibuster to block every major nominee by the Obama administration, to the DC Circuit, the NLRB, and to many other vital posts, that we ultimately, as a Democratic caucus, felt compelled to make that change,” Coons told CNN on Thursday. “What I regretted was that we had a dysfunctional Senate where the minority leader and minority caucus at the time, the Republican caucus, so thoroughly and effectively misused the filibuster to block President Obama, that we ultimately took the step of changing that rule in the Senate.”

That’s the equivalent of a bank robber regretting that the bank made him do it, by keeping all that money there.

Democrats weakened the filibuster rule, yet now they need it to do exactly what the Republicans did – oppose a strong majority.

They knew they could be in this position someday. In 2013, when the rule was changed, then-Senate Majority Leader Harry Reid said as much.

“The changes that we made today will apply equally to both parties,” Reid said at the time. “When Republicans are in power, these changes will apply to them as well. That’s simple fairness. And it’s something both sides should be willing to live with to make Washington work again, that is also simple fairness.”

That’s now a reality for the Democrats.

“With their power weakened, Democrats are weighing how to make life difficult for the Senate GOP,” CNN explained last week. “They are planning on making the fight over Rep. Tom Price’s nomination to lead the Health and Human Services Department a proxy war over the GOP’s plans to dramatically overhaul Medicare. They want to turn Steven Mnuchin’s nomination to lead the Treasury into a battle over regulating Wall Street. And they want to make Sen. Jeff Sessions answer for his hard-line stands on civil rights issues and against comprehensive immigration reform.”

With each new cabinet appointment by Trump, the Democrats howl even louder and their regret seems to deepen.

The truth is we’re in good-and-gander territory. In theory, the Republicans should support a move to change the rule back; a too-powerful majority is bad for everyone. The framers of the Constitution knew that, and built in checks and balances. The filibuster is an effective one.

But practically, Republicans know they can’t change the rule back – because when the pendulum swings again, as it inevitably will, the Democrats won’t hesitate to seize that power again.

So Democrats brought this on themselves. They may says the had no choice, but now they have less power.