Former U.S. Attorney J. William Roberts and former Illinois Attorney General Tyrone Fahner will scrutinize possible candidates' credit histories and perform criminal background checks.
Illinois GOP spokesman Jason Gerwig says the party just wants to make sure the person who's selected is ready to go.
The party is mulling over replacements for Ryan, who dropped out of the race Friday amid accusations he tried to pressure his then wife to have sex in public. Ryan denied the allegation.
Many well-known Republicans have said they won't run, so the party has an increasingly short list of candidates with the strong name recognition needed to challenge Democratic state Senator Barack Obama.