Illinois state Rep. Beth Coulson, a Republican moderate, will announce Aug. 24 that she is running in the 10th district open-seat race, according to two sources familiar with her campaign.Coulson’s official entrance further crowds the field for Republicans, who are looking to hold on to Rep. Mark Kirk’s (R-Ill.) suburban Chicago district in 2010. Kirk, a leading GOP moderate in the House, has held the seat for five terms, even though his district has voted increasingly for Democrats in local, statewide and national races.But House Republicans have indicated that they are prepared to fight to keep the seat in GOP hands. National Republican Congressional Committee Recruitment Chairman Kevin McCarthy (Calif.) visited the district last weekend as part of a recess road trip to meet prospective candidates. In addition to Coulson, several businessmen have also indicated their interest in the race. Businessman Dick Green has hired consultants and filed exploratory papers, while attorney Bill Cadigan — a former staffer for Kirk’s predecessor, ex-Rep. John Porter (R) — has also filed paperwork with the Federal Election Commission.McCarthy met with Green, Cadigan and another interested potential candidate, businessman Bob Dold (R), last weekend, according to a report in the Chicago Tribune.Coulson is likely to be the most liberal Republican in the field, and she is considered even more ideologically moderate than Kirk. According to a source close to Green, he is more conservative than Kirk but still moderate on social issues.Coulson’s fundraising skills, however, remain untested. While running for legislative office, Coulson could take advantage of liberal state fundraising laws. Several local Republicans questioned whether she will be successful in raising money under federal contribution limits.Green, meanwhile, has indicated that he is willing to put some of his personal financial resources into the race.The 10th district is notoriously expensive for campaigns because it is covered by the Chicago media market.Democrats will also likely have a primary to determine their 10th district nominee. State Rep. Julie Hamos and the party’s 2006 and 2008 nominee, marketing consultant Dan Seals, have both announced their candidacies.The Illinois primary is scheduled for Feb. 2.