竞选联邦眾议员初選失败后，奧巴馬專注於自己的州参议员工作，编撰要求对可能判[[死刑]]罪犯的审问必须录像的法律<ref>{{cite news|url=http://www.newyorker.com/fact/content/?040531fa_fact1 |title=The Candidate: How the Son of a Kenyan Economist Became an Illinois Everyman |work= |language=en|publisher=纽约人网 |author=William Finnegan |date=2004-05-31|accessdate=2007-01-21}}</ref>。2002年，他竞选连任伊利诺州参议员，未遇对手<ref>{{cite news|url=http://www.elections.il.gov/ElectionInformation/GetVoteTotals.aspx |title=Vote Totals, General Election 2002, 13th Senate |work= |language=en|publisher=伊利诺伊州选举网|date=2002|accessdate=2007-01-21}}</ref>。2003年1月，当民主党重新取得议会的控制权，他經提名成为州卫生与公众服务委员会主席。在他的立法提案中，他帮助编撰《工作所得抵税法》，为低收入家庭提供援助，还致力于为一些无法承担健康保险的居民起草相關立法项目，更協助通过增加对[[艾滋病]]预防和病人照料的项目預算<ref>{{cite news|url=http://www.ilga.gov/legislation/legisnet90/sponsor/OBAMA.html |title=Bills and Resolutions Sponsored or Cosponsored by Barack Obama|work=|publisher=伊尔加政府网|language=en|date=1997–1999|accessdate=2007-01-21}}</ref><ref>{{cite news|url=http://www.ncsl.org/programs/health/cancerch.htm|title=State Legislation Relating--|work=|language=en|publisher=NCSL网|date=2002-07-01|accessdate=2007-01-21|deadurl=yes|archiveurl=http://webarchive.loc.gov/all/20011116000812/http://www.ncsl.org/programs/health/cancerch.htm|archivedate=2001-11-16}}</ref><ref>{{cite news|url=http://www.ilga.gov/legislation/legisnet92/sponsor/OBAMA.html |title=Bills and Resolutions Sponsored or Cosponsored by Barack Obama |work= |language=en|publisher=伊尔加政府网|date=2001–2003|accessdate=2007-01-21}}</ref>。

== 总统之路 ==