Freshman Democratic Rep. Brad Schneider raised $390,000 in the first quarter of this year.
Cash-on-hand figures were not immediately available. But at the end of last year, Schneider reported only a small amount, $14,000, in the bank.
The 10th District, which includes the suburbs north of Chicago, has played host to highly competitive races for several cycles. Last year, Schneider defeated GOP Rep. Robert Dold by 1 point.
Republicans hope Dold will challenge Schneider to a 2014 rematch.
(See also on Roll Call: Top 5 House Rematches to Watch (So Far))
But the 10th District might be moving out of reach for the GOP. Now-Sen. Mark S. Kirk, a Republican, held on to the seat for a decade, but President Barack Obama carried it by overwhelming margins.