Giannoulias' campaign announced Tuesday he raised $1.2 million in the first three months of the year. That's significantly less than the $2.2 million raised by Republican Mark Kirk.

Still, it was Giannoulias' best fundraising quarter.

Giannoulias has denied any "softness" in his fundraising because of highly publicized problems at his family's bank that could be on the verge of collapse.

Obama's old seat would be a plum election prize for Republicans.

In an e-mail to supporters, Giannoulias says he wants to recruit 10,000 new grass-roots donors by May 15. He's asking people to donate as little as $5.