We can surmise that Democrats are preparing for impeachment because they chose Rep. Jerrold Nadler (N.Y.) as the ranking Democrat on the House Judiciary Committee — and Nadler is an expert in constitutional law. As Kane reports, this is the “clearest sign yet of how seriously House Democrats consider the possibility of a full-blown constitutional showdown” with Trump, one that could “end with impeachment proceedings.” Or, as Rep. Gerald E. Connolly (D-Va.), put it, Nadler won the slot because of the “constitutional argument” and because of the need for Democrats to “prepare for the coming storm.”

This is the right posture — for a number of reasons, some obvious, some less so. To be clear, I’m not necessarily saying impeachment is merited right at this moment. My position aligns with the persuasive argument made by Benjamin Wittes and Jane Chong that there are ample grounds for beginning a formal congressional inquiry into possible impeachment, based on the sum total of Trump’s multiplying fields of misconduct.

Publicly, Democratic leaders are urging the rank and file to play down any talk of impeachment, out of fear that it might be perceived as overreach. But there is no reason for Democrats to be apologetic about preparing for possible impeachment in certain plausible scenarios, or to shy away from treating that as a legitimate topic of public debate.

First, it’s just obviously true on the merits that we should be at least discussing the subject. Trump’s ongoing self-dealing and abuses of power, the facts being unearthed in the Russia probes, the obvious efforts earlier this year to hamstring the FBI investigation, the blithe lack of concern about future assaults on our democracy, the uncontrollable contempt for governing norms and the rule of law, and the profound inability to grasp the most basic obligations that come with his office — both to the public and to the integrity of our system of government — plainly add up to an aggregate level of degradation that commands a serious effort to determine whether he is fit to continue. As Andrew McCarthy put it in National Review, even if we don’t know enough yet to determine whether Trump should be impeached, it is self-evidently a “question worthy of exploration.”

Second, it’s perfectly plausible that there actually will be a constitutional crisis in coming weeks or months. We don’t know if Trump will try to remove special counsel Robert S. Mueller III, but some of his friends and advisers believe this a genuine possibility: Trump’s lawyers are telling him he’ll be exonerated soon, but if not, Trump may go into “meltdown.” If that happens, we just don’t know how congressional Republicans will respond. Right now, they should be sounding a loud, clanging alarm, and they simply are not doing this in any meaningful sense.

Even if it doesn’t happen, Mueller could end up finding very serious, albeit not criminal, wrongdoing. We don’t know how Republicans would respond to that, either. If Republicans punt in either scenario and don’t act in the face of obviously impeachable offenses, Democrats will have to take the lead in making a big case to the country about why Trump’s aggregate misconduct has crossed over into a legitimate basis for undoing the effects of the election. This is a difficult and complicated business, and Democrats should be preparing for it, with a current effort to grapple with the totality and larger significance of that misconduct, which is, if anything, mounting.

It is perfectly possible, of course, that neither of those scenarios will come to pass. But even so, Democrats should still be talking about these matters, right now, if only because the public deserves a serious discussion of what is happening in our politics in a broader sense, not just at the hands of Trump’s offenses but also amid the Republican Party’s enabling of those offenses. Democratic strategist Simon Rosenberg tells me he has held private discussions with many congressional Democrats, and has found a “hunger” for the party to “go bigger” on the idea that “something very fundamental is at stake” in our current moment. Said Rosenberg: “Democrats have to find the right voice for this time of enormous challenge.”

It is often argued that Democrats should stick to jobs and the economy, and not talk too much about Trump’s behavior. Tom Steyer’s ads calling for impeachment have been derided as a big waste of money. But someone has to be staking out the outer boundaries of this conversation. If some individual Democrats feel politically constrained from talking too directly about Trump’s fitness to serve, that’s understandable. But generally speaking, this moment is potentially too consequential for the party to retreat into squeamish message-tailoring. Whatever is going to happen, Democrats should rise to the occasion and treat it with the gravity and ambition it commands.

* MUELLER IS LOOKING AT POSSIBLE TRUMP OBSTRUCTION: Foreign Policy magazine reports that the White House counsel has turned over documents to Mueller that suggest the White House may have known that national security adviser Michael Flynn had lied to federal investigators well before Trump fired him. The report says Trump may have been briefed on this, which could “bolster any potential obstruction of justice case” against the president.

We already know Mueller is looking at such possible obstruction. And as I’ve noted before, the question of whether Trump directed Flynn to lie to the FBI is a central unknown, one that Mueller appears to be examining.

* ASKED IF MUELLER IS IMPARTIAL, PENCE DODGES: Last night on Fox News, Vice President Pence was repeatedly pressed to say whether he has confidence that Mueller’s probe is fair and impartial. He twice refused to answer the question, instead repeating that the White House is “fully cooperating” with the probe.

This is just a clever double game, in which the White House claims it has no nefarious intentions toward the probe, while winking at all the outside allies who are casting it as not just illegitimate but a coup in the making against Trump.

* DEMS HOLD WIDE GENERIC-BALLOT LEAD: A new Politico-Morning Consult poll finds Democrats leading by 10 points in the generic House ballot matchup, 44-34, the largest of the year. A summary of other polls:

A CNN poll out this week gave the party a stunning, 18-point lead. Surveys from Monmouth and Quinnipiac universities showed Democrats ahead by 15 points. An NBC News/Wall Street Journal poll showed voters prefer a Democratic-controlled Congress to a Republican one by an 11-point margin.

As Politico notes, a lead in the high single digits would probably be enough to flip the House, despite gerrymandering and other GOP structural advantages.

* HUGE TAX CUTS UNLIKELY TO HAVE BIG EFFECT: Republicans keep saying the corporate tax cuts will unleash an explosion of investment, leading to growth and higher wages. The New York Times punctures the claim:

Tax cuts can provide an added incentive to invest. But as most chief executives acknowledge, they are generally not the crucial factor. Investment decisions are much more closely linked to demand for goods and services or technological advancement. As it is, manufacturers are not making full use of the capacity in their existing facilities.

As one analyst tells the Times, if the economy accelerates, the big question will be whether that was going to happen anyway. Trump will say it was all his doing, naturally.

* STATES MAY TAKE LEGAL ACTION AGAINST TAX BILL: Reuters reports that Democratic-led states that will get hit hardest by the tax plan (they have high taxes and deductions are now limited) may take legal action. It’s unlikely to work. But:

Even though such lawsuits would face long odds they could help galvanize Democrats for next year’s mid-term election. … Some political strategists see a win for Democrats regardless of how courts ultimately rule, saying that lawsuits could be used to keep the issue front and center for voters already largely disenchanted with the Republican party.

And Democratic anger at the tax bill is going to be a big motivator next fall, believe me.

* LIES, LIES AND MORE LIES ABOUT TAX BILL: The Associated Press has a good fact check of all the lies, mostly told by Republicans, about the tax plan. Trump falsely calls it the largest tax cut in history, and Pence calls it a “middle-class miracle.” Reality:

The nonpartisan Tax Policy Center estimates the biggest benefit of the new law will go to households making $308,000 to $733,000. Households making over that should get a tax cut worth 3.4 percent of their after-tax income. For the richest 0.1 percent (making over $3.4 million), the tax cut should be worth 2.7 percent of their after-tax income. For middle-income earners: 1.6 percent, the center estimates.