IRS Commissioner Chuck Rettig was officially sworn in this week and is being pressed by Senate Democrats to defend and enforce a provision in the tax code that bans churches and other 501(c)(3) nonprofit groups from engaging in political activity.

The Johnson Amendment, which has been in place since 1954, prohibits churches and other groups from endorsing or opposing political candidates. The Trump administration and Vice President Mike Pence in particular have vowed to do away with the provision or at the very least stop enforcing it.

In a letter to Rettig this week, Senate Finance Committee ranking member Ron Wyden (D-OR) called on the commissioner to commit to enforcing the law.

“These critical protections have for more than 60 years insulated the charitable organizations serving our communities from increasingly rancorous political campaigns,” Wyden said.

Rettig has not responded to the letter as yet but did say during his confirmation hearing that he would ensure the IRS enforces the law “in an impartial and nonbiased manner.”