The Senate Finance Committee will investigate the IRS over its scrutiny of Tea Party groups, the panel’s chairman said Monday.

Sen. Max Baucus (D-Mont.), whose powerful committee has jurisdiction over taxes, called the IRS’s actions an “outrageous abuse of power and a breach of the public’s trust.” He said “targeting groups based on their political views is not only inappropriate but it is intolerable.”

“Americans expect the IRS to do its job without passion or prejudice,” Baucus said. “We need to get to the bottom of what happened here.”

The chairman’s statement comes just days before the Treasury Department’s inspector general for tax administration is expected to release an audit on the IRS’s treatment of Tea Party groups.