This diary mainly compiles and summarizes information from Project Vote Smart. Interest Groups, as used in the title and the referenced website, refers to single issue groups such as "NARAL Pro-Choice America" and "National Right to Life Committee". Some are progressive and some conservative; if not their names, the support (percentage) of the candidates will help you tell them apart. Where other sources are used, links or notes are provided.
In the interest of brevity and focus on the most likely nominees, I have only included Clinton, Edwards and Obama. To keep the diary as short as possible, I have only included issues I considered most important and groups I thought most prominent for each issue. I have also excluded data where the position of all 3 named candidates has been identical (e.g., Clinton, Edwards and Obama supported the interests of the Planned Parenthood 100 percent while in the US Senate). In attempt to make this an "apples to apples" comparison, I am only comparing candidates' records in the US Senate, and where possible, Clinton vs. Edwards and Clinton vs. Obama for the identical periods of time.
Abortion Issues - National Family Planning & Reproductive Health Association - 2005-2006
Clinton: 93% - Obama: 100%
Taxes - National Taxpayers Union - 2006,2005 -- 2003,2002,2001
Clinton: 17%,9% -- 21%,17%,3%
Edwards: N/A -- 22%,18%,13%
Obama: 16%,6% -- N/A
Business - Business-Industry PAC - 2006,2005 -- 2003,"2001-2002"
Clinton: 27%,11% -- 13%,05%
Edwards: N/A -- 00%,05%
Obama: 10%,15% -- N/A
Conservative - American Conservative Union - Lifetime Rating, 2005 Rating
Clinton: 09% - 12%
Edwards: 10% - N/A
Obama: 08% - 08%
Environment - League of Conservation Voters - 2006,2005 -- 2003, "2001-2002"
Clinton: 71%,95% -- 89%,88%
Edwards: N/A -- 37%,68%
Obama: 100%,95% -- N/A
Public Health - American Public Health Association - 2006,2006 -- 2003,2002,2001
Clinton: 100%,80% -- 100%,100%,100%
Edwards: N/A -- 100%, 71%,100%
Obama: 100%,80% -- N/A
Liberal - Americans for Democratic Action - 2003,2002,2001
Clinton: 95%,95%,95%
Edwards: 65%,70%,95%
Liberal - National Journal, Composite Liberal Score - 2006
Clinton: 70.2%
Obama: 86%
Pro-Israel foreign policy - Haaretz
Clinton: 7.62 (of 10)
Edwards: 5.87 (of 10)
Obama: 5.00 (of 10)
National Security Issues - Center for Security Policy - 2005-6, 98-2002
Clinton: 32%, 56%
Edwards: N/A, 50%
Obama: 21%, N/A
Civil Liberties: ACLU - Lifetime rating
Clinton: 72%
Edwards: 50%
Obama: 79%
I did not try to explain the particular vote where a group's interest was (or was not) supported by a candidate, though that would obviously be informative and a welcome update to the diary if I or anyone else can find and compile that information.