There are no ready answers. But I remember that two cases were filed against late Prime Minister Shri P.V. Narshimah Rao.
One case was filed by an NRI Lakhubhai Pathak.
He alleged that he made some payment to a middleman, on being assured of some benefits. But later, it did not happen.
He complained being cheated. IPC 420.
On death of Lakhubhai, this case was closed.
Another case I remember, in Rajkot in Gujarat, someone filed complaint against Shri Rao that certain election promises were made but not fulfilled.
He complained Cheating. IPC 420.
The Brave Magistrate issued summons against the then Prime Minister of India.
But next-day, his superior judge, cancelled his order and then cancelled case itself.
I remember only these two cases where criminal law IPC 420 was invoked against ministers who may have violated Poll Promises or other promises.
The Lawyers need to evolve law on this issue. The public wants to know more.