If one strips a church of tax exempt status then that church is also freed from any restrictions on political advocacy and activity. Churches explicitly backing certain candidates? Sounds OK to me.
Churches are already free to engage in all the political activity they want. Even before Trump/Congress passed a law guaranteeing churches the right to political activity on their property, the IRS admitted they had no authority to prosecute churches for it. However, that doesn’t seem to have been effective in getting priests to speak up at all. (Yes, corruption, plus Americans United for Separation of Church and State continues to foment confusion.)