Attorney General Eric HolderEric Himpton HolderAll eyes on Garland after Bannon contempt vote Arkansas legislature splits Little Rock in move that guarantees GOP seats Oregon legislature on the brink as Democrats push gerrymandered maps MORE can expect tough questions from a top Republican when he appears Thursday before Congress.

Rep. Darrell Issa (R-Calif.) will press Holder on why he has not appointed a special prosecutor to investigate allegations the Obama administration offered Rep. Joe Sestak (D-Pa.) a top Defense Department job in exchange for staying out of the Pennsylvania Senate race.

Issa, the ranking member of the House Oversight and Government Reform Committee, will use his question time during a House Judiciary Committee hearing to press Holder on the matter, Issa's office said.

The California Republican has been calling for a special prosecutor for several weeks now, and his office said Holder has not responded to a letter requesting the special prosecutor.

Issa's picked up on remarks Sestak has made, claiming White House officials had approached him about a job in exchange for dropping his primary challenge to Sen. Arlen Specter (D-Pa.). The allegations, if true, could violate federal election laws, Republicans say.

Tomorrow's questioning also comes during the waning days of that primary battle between Specter and Sestak. Pennsylvania voters will head to the polls Tuesday to pick a winner in the primary, and polls have shown Sestak closing a once-sizable gap between him and the veteran senator.