Durbin said more than 115,000 Illinoisans lost benefits due to Republican actions.
Giannoulias accused Kirk of repeatedly voting against unemployment benefits.
"Congressman Kirk's votes against extending jobless benefits should be read for what they are, an outright assault against people who are desperate to work and who need help right now," Giannoulias said.
In a statement, Kirk denied the charges, saying he had repeatedly voted in favor of unemployment benefits.
The new benefits will add $34 billion to the deficit. Kirk accuses Giannoulias of going back on promises to be deficit neutral.
He says Giannoulias' commitment to responsible spending was short-lived.