Voting on the Hall of Fame's Facebook site will conclude at 5 p.m. ET on Sept. 30. Nationals broadcasters Charlie Slowes and Bob Carpenter are two of 75 candidates.
The top three fan selections will appear on the final 10-name ballot for the award, from which the winner is selected by a 20-member electorate. The winner will be announced at baseball's Winter Meetings in Dallas in December.
The Ford C. Frick Award has been presented annually since 1978 for excellence in baseball broadcasting, and is given to an active or retired broadcaster with a minimum of 10 years of continuous Major League broadcast service with a ballclub, network or a combination of the two.