For transcripts of news broadcasts and speeches produced in the last 30 years use:

• Nexis Uni provides access to many major news broadcasts and political transcripts. Choose Sources from the top menu and search for transcripts.
• Factiva also has a collection of transcripts. Select Search, then Search Builder from the top menu. Open up "All Sources,” use the pulldown menu to select "By Type," and select Transcripts: All, or select a particular type (broadcast, corporate, government). Or, type rst=ttpt AND "your search terms" into the Free Text Search box.
• Newsbank is another news resources that includes transcripts. From the A-Z Source List, select Type from the drop-down and search for transcript.