We've actively lobbied for that for years--Republicans have refused, because they know that the people working low-income jobs whose managers will not let them off to go vote tend to lean Democratic.

There are some states where the best we've managed is being allowed to take "unpaid" time off to go vote, with the caveat that your employer cannot fire you for doing so. Some states don't even have that much. Guess which way those states tend to vote.