Likewise, states cannot place term limits on senators or congressmen, as litigated decades ago in federal court.
Bottom line: no recall, no impeachment, either by voters or state legislatures. A senator can be removed by failure to re-elect, resignation, death, or expulsion by two-thirds of the Senate, but by no other means.
I am well aware of that; I merely was responding to the prior post, which proposed amending the U.S. Constitution to permit recalls by stte legislatures.