Senate appointee Roland Burris helped Illinois Gov. Rod Blagojevich in his 2006 reelection bid by collecting opposition research against his GOP opponent.
Burris made several requests for thousands of pages of documents linked to state Treasurer Judy Baar Topinka, which Blagojevich could use as ammunition.
Such assistance would typically draw little notice. But it comes to light as Burris is seeking to project his independence from the scandal-plagued governor.
On Friday, Burris' lobbying partner, Fred Lebed, acknowledged they helped the Blagojevich campaign by writing the letters to the treasurer's office under the Freedom of Information Act.
"At one point or another every Illinois Democrat ... [has] worked toward electing Rod Blagojevich," Lebed said.