Byrd, 87, the longest-serving member of Congress and a harsh critic of the war in Iraq, said his TV effort launched last week answers the GOP group's "slick out-of-state ads" that use trickery and falsehoods.
The GOP ads began in late July in the Charleston-Huntington area of West Virginia.
A spokesman said Byrd's effort will track the GOP's in "geography and duration," the Charleston (W.Va.) Gazette reported.
In a spot titled "Truth," an Iraq war veteran said Byrd is fighting for West Virginians.
"Byrd can't handle the 'Truth,' " the National Republican Senatorial Committee said in response.
Byrd's quick counterattack shows "he learned the lesson John Kerry didn't learn," West Virginia Wesleyan's Robert Rupp said.
While three Republicans announced they plan to run in the general election 15 months from now, political observers awaited the fall decision of Rep. Shelley Capito, R-W.Va.
Byrd has yet to announce if he will run for re-election.