In a room full of faith leaders Thursday, President Donald Trump echoed a campaign promise to "get rid of and totally destroy" the Johnson Amendment. 

While the line was well-received at the National Prayer Breakfast in Washington, D.C., outside observers pounced — saying that altering the provision would threaten the sanctity of America's separation of church and state and raise issues of religious lobbying.

Doing away with the Johnson Amendment, however, won't be so simple. 

Essentially, it's supposed to stop leaders of houses of worship from using the pulpit to campaign for certain politicians. 

In a broader sense, it affects 501(c)(3) tax exempt organizations — which includes not only religious institutions, but charities and universities — and says they can't participate in or wield an influence in political campaigns.