In these instances, the state constitution will declare which official is to serve as governor and whether this person will have all of the powers of the office or only specified ones.
Following the resignation of Christine Todd Whitman in 2001 to become EPA Administrator, Donald DiFrancesco assumed the acting governor's post, serving until January 2002.
Following DiFrancesco's departure from the senate, John O. Bennett and Richard J. Codey each served as acting governor as well.
These unusual events were a major factor in voters' decision to amend the state constitution to create the office of lieutenant governor in the 2005 referendum, effective with the 2009 election.
Before the amendment could take effect, state transportation commissioner Kris Kolluri served as acting governor the day of December 28, 2006.
Then-Senate president Earl Ray Tomblin is the first person under the current state constitution to act as governor following the November 15, 2010 resignation of Joe Manchin following his election to the United States Senate seat vacated by the death of Robert Byrd.
As there was more than one year remaining on Manchin's term as governor, a special election was held, which Tomblin won.
When he was campaigning out of state, which was often in late 1979 and early 1980, Mike Curb, a Republican who was then serving as lieutenant governor of California often used his position as acting governor to veto legislation, promulgate executive orders, issue proclamations, appoint Republican appellate court justices, and to do other things that Brown would not likely have done had he been present in the state.