Our peculiar election system made from compromises over time and a distrust of direct democracy has led us to where our President-elect was elected despite losing the popular vote.
And the compromises that led us to the Representative and Senatorial bodies have given us a Senate led by Republicans despite the fact that they represent about 44% of the population versus the Democrats representing 55%. (This is assuming Republicans take the Louisiana seat that will be decided in December).
So any talk of a mandate by the Republicans is pure hypocrisy.