Republican state Sen. Randy Hultgren led Rep. Bill Foster (D) by 6 points in a new poll taken for the Republican’s campaign. Foster won the seat in a March 2008 special election after former Speaker Dennis Hastert (R) retired.

The poll showed Hultgren with 44 percent of the vote and Foster with 38 percent. Sixteen percent of voters were undecided, and 4 percent chose Green Party nominee Daniel Kairis. The Tarrance Group, a Republican firm, surveyed 400 likely voters Oct. 3-4, and the poll’s margin of error was 4.9 points. Neither the campaign nor the Tarrance Group released any other numbers from the poll.

The poll showed a slight improvement for Hultgren over similar polls conducted for the campaign in May and September.

Much has changed in the race in the past month. Foster went up on broadcast TV in late September in the expensive district directly west of Chicago, and the National Association of Realtors and the Democratic Congressional Campaign Committee are airing cable ads on his behalf. The Democrat’s campaign accused Hultgren’s investment firm of profiting off the federal bailout in an ad.

Both Hultgren and the National Republican Congressional Committee are airing ads on cable. The two candidates have tangled over campaign donations.