Search under "Members & Committees" > "Members Records" to find voting records, financial disclosures, campaign contributions and campaign finance reports. Most data sets will cover 1989-present.
In addition to the Basic Subscription, BU Libraries has access to the full text of the Congressional Record and its predecessor publications from 1789-present, the Congressional Serial Set from 1789-2010, Serial Set maps from 1789-present, Executive Branch Documents, 1789-1932, and Congressional Research Service reports.
Opensecrets.org (Center for Responsive Politics)
Tracks the political money to make a direct link from campaign donations to votes and public policy decisions of elected officials. Huge source of raw data, including 527 forms, campaign finance data, lobbying data and personal finances.
Campaign Finance Institute Non-partisan organization that studies campaign finance, issues reports, and makes recommendations. Provides data on campaign finances and information on state and federal laws.