Yes, I recall reading something about that. The GOP (stupidly) signed some sort of agreement where they waived their rights to make such challenges.
Which is, of course, very ironic. Historically, it was the Democrats who tried to prevent blacks from voting. Ike did a lot to help the blacks, and it was LBJ who condemned them to generations of poverty. But LBJ knew that would capture the black vote, and that was all that mattered.
The GOP hasn’t had any backbone for a long time.