Is it permissible to pray behind an imam who smokes?

If it is possible not to present a smoking Imam for the imamate, then he should not be presented. But if preventing him would lead to a greater harm, then he should not be prevented; rather, one should pray behind him, and prioritizing the righteous is better. If performing Friday prayers and congregational prayers is not possible except behind a transgressor, then the prayer should not be repeated.