There is the one and only crime which is defined in the United States Constitution. The definition is found in Article III, Section 3, Clause 1, and the relevant language is very clear:
Treason against the United States, shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort.Let's break that down and apply it to this situation.
"Treason against the United States, shall consist only..."
That phrasing unequivically establishes that the clause is both the definition of treason and that it is the only definition of treason - in other words, if the acts don't fit the rest of the definition, they aren't treason.
"...in levying war against them..."
Mitch McConnell did not levy war against the United States. Metaphorical war only counts if you want to metaphorically charge him with metaphorical treason. It doesn't work in the real world, and shouldn't. I'll get to why in a minute.
"...or in adhering to their enemies, giving them aid and comfort."
The provision does not say "giving aid and comfort to another country." We are not at war with Russia. Russia, therefore, is not legally our enemy. if Russia is not an enemy, giving Russia aid an comfort cannot be treason. It's really that simple.
Now I could get into all kinds of caselaw, discuss whether McConnell's inaction would fit the definition in the event that Russia was an enemy (it doesn't), and so on, but that would use more of my time than I care to spare on this absurdity. McConnell's decision to refuse to join in a united, bipartisan effort to call out Russia's attempts to influence our election was exactly the kind of thing that you would expect from the king of obstructionism, but it's simply not treason. And it's not treason for good reason.
It's not an accident that treason is defined in the Constitution, or that it's defined as narrowly as it is. That's a feature, built in by the founders, as James Madison (writing as Publius) explained in Federalist 43:
But as new-fangled and artificial treasons have been the great engines by which violent factions, the natural offspring of free government, have usually wreaked their alternate malignity on each other, the convention have, with great judgment, opposed a barrier to this peculiar danger, by inserting a constitutional definition of the crime, fixing the proof necessary for conviction of it, and restraining the Congress, even in punishing it, from extending the consequences of guilt beyond the person of its author.
In short, the founders didn't want groups of Americans throwing reckless charges of treason around as a way to pound on their political opponents, so they crafted the definition so as to make that impossible.
So, before you sign any of the petitions demanding that McConnell be hung, drawn, and quartered - or the modern equivalent - it might be good if you take a moment to think about what you are doing, and why it's something that the founders considered to be incompatible with the America they were trying to establish.