One-party rule is tyranny.
I think Obama is exposing democrat fear with the statement.
The GOP holds state government super majorities in something like 23 or 24 states with the democrats holding super majorities in half as many with the rest being mixed.
Where democrats hold super majorities are in those heavily populated liberal states.
The fact is, if we went back to before the 17th amendment, republicans would hold 2/3s to 3/4s of the senate.