It is astonishing, really.

The president of the United States has accused the U.S. Chamber of Commerce, despite its denial and without supporting evidence, of illegally funneling foreign money into U.S. campaigns. “Just this week,” Barack Obama said recently about the chamber, “we learned that one of the largest groups paying for these [political] ads regularly takes in money from foreign corporations. So groups that receive foreign money are spending huge sums to influence American elections.”

On CBS’s Face the Nation, host Bob Schieffer asked David Axelrod, senior adviser to the president, if there is any evidence to support their accusation. Axelrod responded this way: “Well, do you have any evidence that it’s not, Bob?”

Likewise, Obama’s press secretary, Robert Gibbs, wouldn’t back away from the incendiary charges yesterday. “The president will continue to make the argument that we don’t know where this money comes from and entities like the Chamber have said they get money from overseas,” Gibbs told reporters at the White House.

Set aside the hypocrisy of this whole episode. (My former White House colleague Ed Gillespie points out that no Democrats, least of all Obama, expressed concern about such outside spending in 2008, when more than $400 million was spent to help elect Barack Obama, much of it from undisclosed donors.) Set aside the fact that Mr. Axelrod concedes that the chamber is abiding by long-standing rules, that it doesn’t have to disclose its donors list, and that no other organizations are disclosing theirs. Set aside the fact that the chamber has 115 foreign-member affiliates who pay a total of less than $100,000 in membership dues to a group whose total budget is more than $200 million. And set aside the fact that various news organizations have dismissed the charges, including the New York Times, which reports, “a closer examination shows that there is little evidence that what the chamber does in collecting overseas dues is improper or even unusual, according to both liberal and conservative election-law lawyers and campaign finance documents.”

What we are witnessing is the abuse of power. We are now in a situation in which the president and his most senior advisers feel completely at liberty to throw out unsubstantiated charges and put the burden on people (and institutions) to prove their innocence. Liberals once referred to such tactics as McCarthyism. But Joseph McCarthy, for all his abuses, was “only” a United States senator, one member out of 100. The president and his advisers, on the other hand, have at their disposal far more power and the ability to inflict far more injury.

What Obama and his aides are demanding is that the Chamber of Commerce prove a negative — and in doing so, they are trying to intimidate the chamber into disclosing what is, by law, privileged information. “If the Chamber doesn’t have anything to hide about these contributions,” Mr. Axelrod says, “and I take them at their word that they don’t, then why not disclose? Why not let people see where their money is coming from?”

Let’s see if we can help Mr. Axelrod out by providing him with an explanation.

For one thing, he is employing the guilty-until-proven-innocent argument. For another, the White House’s standard is being selectively applied. And it encourages slanderous charges because it forces innocent people to disprove them. All this is troubling in any case; but it is triply pernicious when it is practiced by those with unmatched power, because they have an unparalleled capacity to intimidate American citizens.

In further answering Axelrod’s argument, consider this thought experiment. It’s the year 2021, and a partisan critic of a future president repeatedly asserts that the president is addicted to child pornography. It turns out that the critic has no proof of the charge — but when told he is asking the president to prove a negative, he responds: “I take the president at his word. But just to be sure, we’d like to examine his phone records and text messages, his computer accounts, and his credit card receipts. What we want, in other words, is full access to all the relevant information we need. After all, if he’s innocent, why not disclose this information? Why not let people see what you’re doing with your life and free time?”

It must be obvious to Messrs. Axelrod and Obama that what they are doing is irresponsible, dangerous, and deeply illiberal. It’s important to note, however, that this libel is taking place within a particular context. The attack on the Chamber of Commerce is only the most recent link in a long chain. The Obama White House has targeted Karl Rove, Ed Gillespie, and John Boehner; George W. Bush and Dick Cheney; conservative talk radio; Fox News; the state of Arizona; the Supreme Court (for its decision in Citizens United v. Federal Election Commission); members of the Tea Party; critics of ObamaCare who attended town hall meetings; pharmaceutical, insurance, and oil companies; corporate executives, Wall Street, and the “rich.”

All this ugliness comes to us courtesy of a man who said during the 2008 campaign that “the times are too serious, the stakes are too high for this same partisan playbook”; who told us that we should “resist the temptation to fall back on the same partisanship and pettiness and immaturity that has poisoned our politics for so long”; and who assured us, on the night of his election, “I will listen to you, especially when we disagree.”

Back in October 2009, I wrote about this White House’s burning anger and resentment toward its critics and what it foreshadowed. That inferno is burning hotter than ever – and if it goes unchecked, it will eventually lead to a crisis.

In an August 16, 1971, memorandum from White House Counsel John Dean to Lawrence Higby, titled “Dealing with our Political Enemies,” Dean wrote:

This memorandum addresses the matter of how we can maximize the fact of our incumbency in dealing with persons known to be active in their opposition to our Administration; stated a bit more bluntly – how we can use the available federal machinery to screw our political enemies.

At comparable stages in their first terms, the Obama administration seems to be at least as eager as the Nixon administration to use the available federal machinery to “screw our political enemies.” We know how things turned out for the Nixon administration. President Obama cannot say he hasn’t been forewarned.