Politics, he added, was an "unpredictable profession" and one could only try.
Dr Singh was talking to reporters on the sidelines of a seminar on "Macro Economic Developments in India: Policy Perspectives" at St Teresa's College in Ernakulam.
Responding to a question on the Congress' chances of winning in Himachal Pradesh and BJP-ruled Gujarat, he said, "I think our vice president Rahul Gandhi is doing very hard work and I hope his efforts will be crowned with success. But politics is an unpredictable profession. One doesn't know, one keeps trying."
"Well I can only hope. I am not a prophet," the former Prime Minister said.
Get the latest election news, live updates and election schedule for Lok Sabha Elections 2019 on ndtv.com/elections. Like us on Facebook or follow us on Twitter and Instagram for updates from each of the 543 parliamentary seats for the 2019 Indian general elections.