The campaign of rival candidate David Hoffman lit into Giannoulias for the endorsement.
In a blog post on the campaign's web site Thursday, Daniel X. O'Neil, Hoffman's new media director, chastised Giannoulias for saying he was a candidate for change but who was "no doubt excited about stepping up to the same trough that netted Blagojevich more than a million dollars in campaign cash."
Accepting the SEIU endorsement plays right into the national GOP's strategy of making the race a referendum on the disgraced Blagojevich, O'Neil wrote, and Giannoulias is "serving them up a free punch ... This kind of merry-go-round involving the same cozy insiders doing the same political dance is what's wrong with Illinois politics."
The Hoffman camp tried to make clear that it has no problems with the SEIU's 170,000 Illinois members -- just with their head honcho, Tom Balanoff, who met with Blagojevich about the Senate vacancy but has not been charged with any crime or wrongdoing.
"David's beef is not with the rank and file members," campaign manager Michael Powell told the Huffington Post. "His beef is with Alexi. You can't run as the candidate of change and then be willing to accept the endorsement of the man who acted as Blagojevich's emissary to selling the very seat he's running for. The hypocrisy is breathtaking."