The US House of Representatives recently introduced HR 3600, a bill that would repeal a portion of the IRS 501(c)3 code commonly known as the Johnson Amendment:

The Johnson Amendment was passed by Congress in 1954 [and] states that entities who are exempt from federal income tax cannot:

Participate in, or intervene in (including the publishing or distributing of statements), any political campaign on behalf of – or in opposition to – any candidate for public office.

This portion of law has been used as a tool to prevent churches from engaging in political speech about particular candidates.

Churches had always been tax-exempt, because the government recognized that that which the government taxed it was entitled to control.  It was even considered an inappropriate entanglement with religion (in re judicial interpretation of the First Amendment) to tax religious bodies. 

Starting in 1954, however, Lyndon Johnson created a unique situation in which the government could now control that which it did not tax.

The House bill is entitled, appropriately enough:

To restore the Free Speech and First Amendment rights of churches and exempt organizations by repealing the 1954 Johnson Amendment

The bill would remove the restriction regardless of religious affiliation, meaning any tax-exempt organization would be free to engage in political endorsement or opposition.