Giannoulias, a first-term state treasurer, raised $1 million less than the $2.2 million raised by Republican Rep. Mark Kirk. The two are vying for President Barack Obama's old Senate seat, which would be a plum election prize for the Republican Party in November.
Giannoulias has denied there was any "softness" in his fundraising because of the highly publicized problems at a Chicago bank his family owns that could be on the verge of collapse. Broadway Bank has until later this month to raise about $85 million in new money as part of a deal with regulators.
Giannoulias, who acknowledged Monday that his fundraising would lag behind Kirk's, blamed it on a contested primary that diverted his attention from fundraising and on his pledge not to take money from federal lobbyists and corporate PACs.
Still, it was Giannoulias' best fundraising quarter and topped the more than $1.1 million he raised last year shortly after announcing he was exploring a Senate run.
In an e-mail to supporters, Giannoulias said his campaign wants to recruit 10,000 new grassroots donors by May 15. He's asking people to donate as little as $5.
"We have to defeat Mark Kirk, who has obstructed President Obama at every turn and pledged to lead the fight to repeal health insurance reform," Giannoulias said.
Kirk, a five-term congressman from Chicago's northern suburbs, issued a statement Tuesday thanking residents for supporting his "efforts to create jobs, lower taxes and fight corruption."