Illinois U.S. Rep. Aaron Schock is the subject of an congressional ethics probe in connection with a donation he requested a powerful Houser Republican make to a super PAC during this year’s primary.

For the first time Friday, the House Ethics Committee revealed Schock’s case was referred to the committee on August 30, 2012, but it didn’t specify why the Republican from Peoria is under investigation. A spokesman for Schock told WBEZ Friday the probe is related to a contribution made to a super PAC, first reported last spring.

In April, Roll Call reported that Schock asked House Majority Leader Eric Cantor to donate $25,000 to an anti-incumbent super PAC to help defeat incumbent U.S. Rep. Don Manzullo. Manzullo was running against Rep. Adam Kinzinger.

Federal candidates are allowed to solicit donations for super PACs, which are political fundraising groups free to raise and spend unlimited amounts of cash to influence elections. But they can only ask for up to $5,000.

In April, Schock told Roll Call he’d run his request by election lawyers and had received the okay to ask Cantor to donate.

“This is the next step in an ongoing process,” Shock spokesman Steve Dutton said in a statement Friday. “We remain confident that this matter will be resolved positively.” Dutton wouldn’t confirm the facts of Shock’s case, but referred to the earlier news reports about the contribution.

Schock has been considered a rising star in the Illinois GOP, and his name has been floated in connection with the 2012 governor’s race.