Republicans breathed a sigh of relief over Russia. Then Trump started tweeting again

(CNN)At 6 p.m. ET Wednesday night, Republicans breathed a big sigh of relief.

Deputy Attorney General Rod Rosenstein announced that he had decided to appoint Robert Mueller as a special counsel to oversee the ongoing federal probe into Russia's attempts to influence the 2016 election and any possible collusion between the Russians and the Trump campaign.
Bringing in an independent investigator was the best possible option for Republicans, as many acknowledged in private, hoping to find a way beyond the chaos caused by the investigation and Trump's response to it.
If Mueller found no proof of wrongdoing, Trump -- and the broader GOP -- would have a non-partisan stamp on their claims that there really wasn't anything to see here. If, on the other hand, Mueller found wrongdoing, the Trump Administration would be forced to deal with it and the chips would fall where they may. Sure, the broader GOP might suffer some political blowback from such an outcome but at least it would all be over -- and Republicans could begin to move on.
    That relief held until just before 8 a.m. ET Thursday when Trump, who had been noticeably silent on Twitter over the past 24 hours, picked up his phone again.
    "With all of the illegal acts that took place in the Clinton campaign & Obama Administration, there was never a special counsel appointed!," Trump tweeted. His original tweet, which misspelled "counsel" as "councel," was deleted and tweeted out again with the right spelling at 10 a.m. ET.
    Then he tweeted again. "This is the single greatest witch hunt of a politician in American history!," Trump wrote at 7:52 am.
    But he wasn't done! In a lunch meeting with TV anchors at the White House, Trump again attacked the idea of Mueller's appointment as special counsel." I believe it hurts our country terribly, because it shows we're a divided, mixed-up, not-unified country," Trump said according to CNN's Jake Tapper. He added of the investigation: "It also happens to be a pure excuse for the Democrats having lost an election that they should have easily won because of the Electoral College being slanted so much in their way. That's all this is."
    Out the window was the talk of how "measured" his response had been to the decision by Rosenstein to appoint a special prosecutor. Gone was the idea that Trump understood the gravity of the situation he was now in -- in the wake of revealing classified information to two top Russian officials and reports that he had urged then FBI Director James Comey to drop the case against former National Security Adviser Michael Flynn -- and would act accordingly.
    The tweets this morning should be a reminder -- for roughly the billionth time -- that there is not now nor will there ever be a new or different Trump. The man Donald Trump has been for all of his 70 years on earth is, basically, the man he will be for the rest of his life. (Ask yourself: How many 70 year-olds do you know that fundamentally change who they are? How many 40 year-olds do you know who do that?)
    There is no Trump but Trump. No extenuating circumstances will change that. Not even the appointment -- by his own deputy attorney general -- of a special counsel to look into the Russia meddling will change it. He will prioritize score-settling, responding to slights and popping off whenever he feels like it. Situations and circumstances change. Trump doesn't. Not ever.
    All of which means that congressional Republicans are (still) standing behind the single most unpredictable politician ever to run for president -- much less to be elected president. And that's a scary place to be politically.
    In his two tweets this morning, Trump is clearly trying to make the case that he is being unfairly persecuted and that the special counsel is totally unnecessary. That's all aimed at disqualifying Mueller's findings if they offer something short of full exoneration for Trump.
    "Of course, Mueller said I did something wrong...this whole system has been rigged against me from the start," is something you can easily hear Trump saying if the special investigation produces a result he isn't happy with.
    The problem that presents for Congressional Republicans is that Trump seems to have zero interest in laying low and letting Mueller do his work. Or of accepting Mueller's findings if they are anything short of entirely laudatory of him.
    There will be no ordinary process under Trump. He doesn't do that sort of thing. And that should make Republicans very nervous. Very.