Led by my most able colleague, Rick Lau, we have published three articles on negative campaigning in Senate elections. They will be included in a book we will publish with Rowman and Littlefield in 2004.
Here are the article citations:
"Effectiveness of Negative Campaigning in U.S. Senate Elections," American Journal of Political Science, 46 (January, 2002), forthcoming.
"Effects of Negative Campaigning on Turnout in U.S. Senate Elections, 1988-1998," Journal of Politics, 63 (August, 2001), 804-819.
"Negative Campaigning by U.S. Senate Candidates," Party Politics, 7 (January, 2001), 69-87.