The groups judged how the elected officials voted on issues important to them. Grades were given on a scale of zero to 100, with 100 being the best.
"These rating systems are actually very helpful," said Hannah Geffert, who teaches political science at Shepherd College in Shepherdstown, W.Va.
They can show voters at a glance how the candidates feel about key issues like abortion, she said.
Voters need to understand that the special interest groups are not unbiased. Each one has an agenda they are pushing.
The Americans for Democratic Action has been a leading liberal voice since 1947, the League of Conservation Voters speaks for environmental groups and the League of Private Property Voters speaks for the western-based land-use movement against many laws affecting the environment and public lands.
Not surprisingly, Bartlett got nearly perfect scores from the conservative groups and poor marks from the liberals.
Mikulski and Sarbanes received the opposite ratings - high from the liberal groups and low from the conservatives.
The elected officials were also evaluated by U.S. Term Limits, a Washington, D.C.-based group that solicits and publicizes term limit pledges.
No elected officials in the Tri-State area have agreed to limit their terms, according to the group.
Special interest groups will play a big part in the upcoming election, predicted ratings collector Roll Call Syndicate.
Single-issue groups will bombard voters with political television commercials, known as "issue advocacy ads" or "carpetbagger commercials," Roll Call said.
Some are concerned because the groups are not covered by campaign finance laws.
"They reside in a loophole of the law," said Paul S. Gerrnson, professor of government at the University of Maryland. "This money goes totally unreported and we have no idea where it comes from...It opens up a tremendous avenue for interest groups to participate in campaigns that wasn't there before."
You can find out more information about the special interest groups on the World Wide Web: