WASHINGTON — President Obama said Thursday he is naming a trusted White House budget official, Daniel Werfel, to serve as his new acting IRS commissioner.

The appointment of Werfel comes as a second top IRS official announced Thursday that he is stepping down in the aftermath of revelations that the agency targeted conservative groups for extra scrutiny.

Joseph Grant, commissioner of the agency's tax exempt and government entities division, will retire on June 3, according to an IRS statement. Grant joined the IRS in August 2005 and became the deputy commissioner of the tax exempt division in 2007. He became the second senior IRS official in as many days to offer his resignation.