It goes like this, “Robert Mueller and his investigation into the links between the trump campaign and Russian interference in the last election present a clear threat to the president of the United States.”
Totally ignoring the fact that the only threat that Robert Mueller presents to the trump “presidency” is if in fact trump and his people knowingly worked with the Russian government to illegally subvert a legal US General Election. If trump and his people did nothing then there is no evidence that Mueller can present to the DOJ and Congress for any appropriate legal action. But there are already members of the trump “administration” like Mike Flynn that have pleaded guilty to crimes that are connected with the trump campaign and the Russian government who wanted trump elected so that punishing US sanctions against Russia could be repealed.
One of the first things that Mike Flynn did on learning of the new sanctions imposed on Russia by the Obama administration was to call the Russian ambassador five times in one day, quite likely to work out details on how trump would repeal them as soon as he took office. Something that Flynn then lied to the FBI about, a felony. And something he now says he did on the orders of trump. There’s a link. Or members of trump’s campaign who met with Russian officials during the last election with the express purpose of acquiring material they knew the Russians had stolen from the DNC, another felony.
Then there’s the Steele file, repeated cases of trump staffers failing to disclose intimate and often highly profitable relationships with the Russian government and those close to it.
There’s more than enough grounds for a criminal investigation into the connections between Donald Trump and the Putin government, including trump himself on air openly asking the Russian government to release stolen DNC material to aid his campaign for president.
And there is clearly a need for a special prosecutor on this case because Donald Trump explicitly fired the Director of the FBI to block a criminal investigation into any collusion between trump and Putin to “win” the 2016 election.
The reason that the republicans argument to fire Mueller is idiotic because it implicitly condones treason at the highest level of government. They are in fact saying that being a republican has a higher authority than the US Constitution, they are in effect saying that the law no longer applies to republicans.