WASHINGTON (AP) — A leading Senate Democrat says the Internal Revenue Service's targeting of conservative groups was intolerable, and he is promising to get to the bottom of how it happened.

Senate Finance Committee Chairman Max Baucus made his remark Tuesday as his panel began Congress' second hearing on the extra scrutiny the IRS gave tea party and other conservative groups seeking tax-exempt status.

The Montana Democrat says his committee will follow the facts wherever they lead.

Scheduled to testify to Congress for the first time was former IRS Commissioner Douglas Shulman, who headed the agency for most of the period when it was improperly focusing on the conservative groups.