"This is the single greatest witch hunt of a politician in American history!"

This was President Trump's characteristically sweeping Twitter encapsulation on May 18 of the news maelstrom and investigations surrounding him. These had been capped the previous evening by the appointment of former FBI Director Robert Mueller as special counsel to get to the bottom of Russian election tampering and allegations of allied improprieties or crimes by members of Team Trump.

Trump's official White House statement immediately after the announcement had taken quite a different tone: "As I have stated many times, a thorough investigation will confirm what we already know – there was no collusion between my campaign and any foreign entity. I look forward to this matter concluding quickly. In the meantime, I will never stop fighting for the people and the issues that matter most to the future of our country."

It is a complicated reaction to a tricky problem for Trump. The appointment of a special counsel converts an immediate and explosive threat to his presidency into a quiet, slow-burning conflagration that could direct uncomfortable heat on him and undermine his ability to govern for years to come.

Out of the fire and into the frying pan. Whether this is better or worse for Trump, or for this divided nation, is a question with no single easy answer.

Trump's frustrations are surely to do with the boggling fact that events ever reached this point. It seems highly unlikely to be because there's any real possibility that the Russia investigation will prove his downfall. Not only is there no evidence of election-related criminal wrongdoing, there isn't even a clear idea of what law would have been broken or what crimes are suspected by his critics and anonymous accusers.

Anyone who believes that a Trump-Russia investigation will turn up anything like a promise to make the U.S. a Soviet satellite state, or even anything more incriminating than former President Barack Obama's infamous promise of "flexibility" toward Vladimir Putin's interests, is bound for disappointment.

Still, the very murkiness of the allegations and lack of visible evidence, combined with Trump's overly-accommodating attitude toward Russia, have left much to the public's fertile imagination, which Democrats are happily stoking. Hence the easily jumped-to conclusion that this investigation must be on to something if Trump would go so far as so abruptly to fire an FBI director.

With that bungled step, and with his anonymously alleged but officially denied disclosure of too much information to Russian officials in a White House meeting, Trump has handed Democrats fodder for the torrent of propaganda with which they are sowing confusion over Russia, and fomenting public doubts about the president.

Special counsel Mueller's integrity is widely respected. No one expects him to abuse his investigative power, as other independent and special investigators often have. But the nation's experience with independent investigations during the Clinton and Bush eras has been sour. The result has usually been long, drawn-out probes that produce nothing pertaining to their underlying subject, only prosecutions (or in Clinton's case, an impeachment) for lying or giving false information to the investigators themselves.

Another underappreciated downside of Mueller's appointment is that it further diminishes congressional authority. The use of extraordinary investigators — like bringing in the grown-ups when things get too tough for the kids to handle — encourages public contempt for the branch of government that is supposed to exercise the constitutional power of oversight. Congress, the most democratic branch of government, continues to shrink in its role, devolving into a mere club whose members accept few responsibilities beyond getting themselves re-elected.

Congressional investigations into Russia and allegations of collusion appeared until this week to be proceeding in an orderly and thorough fashion. Now they will be derailed by the special counsel probe. This is deeply regrettable for if members of Congress are truly not up to the task of holding an executive accountable, which we doubt, the Constitution prescribes a remedy, to be administered in large doses at the ballot box in 2018. An extraordinary grant of executive investigatory authority that is "independent" and therefore even less politically accountable than usual is inconsistent with that and unnecessary.

Still, for all the downsides to the appointment of a special counsel, Trump must make these lemons into lemonade instead of complaining about how sour they are. His situation right before Mueller's appointment may well have been precarious enough that he should perhaps be grateful.

The new investigation may permit him and congressional Republicans some breathing room to get back to the business of the governing. One hopes this can right the legislative agenda, although Democrats are determined to prevent that.

But although the appointment of a special counsel may have put Russia on a back burner for a while, the flames there will not be painless.