"Given that delay, the TVA board's plan to delegate temporary authority is wise and should make sure that the delay causes no problems," Alexander said in a prepared statement.
Corker said he met with the nominees last week and is concerned about their fiscal expertise.
"The critical issue for me as I continue to evaluate their backgrounds is whether they have appropriate experience to help guide an $11 billion entity like TVA, which is one of the largest utilities in the U.S.," he said.
Last month, TVA's board chose former Progress Energy CEO Bill Johnson to lead the utility, which provides electricity to 9 million people in Tennessee, Kentucky, Mississippi, Alabama, Georgia, North Carolina and Virginia. Johnson succeeds Tom Kilgore, who is retiring after six years as TVA's president and its first CEO.
The utility's chief operating officer, Bill McCollum, retired in June and was not immediately replaced.
TVA, which receives no taxpayer money and makes no profits, also provides flood control, navigation and land management for the Tennessee River system and assists utilities and state and local governments with economic development.