ALBANY — What do Gov. Cuomo and his Republican challenger Rob Astorino have in common? Both need a lieutenant governor.

One day after current Lt. Gov. Bob Duffy officially announced he will not seek re-election, speculation was rampant over whom Democrat Cuomo will tap to be his running mate as he seeks re-election.

Names that have been mentioned include Buffalo Mayor Byron Brown, Suffolk County Executive Steve Bellone, Long Island Association honcho Kevin Law, Ulster County Executive Mike Hein and even a Republican, Onondaga County Executive Joanie Mahoney.

“At this point, he [Cuomo] must have a short list,” said a longtime Albany Democratic operative who remains close to Cuomo.

The Governor’s Office has not commented. The state Democratic Party will hold its nominating convention on May 21, and Cuomo will most certainly select someone by then.