Theory: A pre-voting, nonpartisan adaptation of Snyder's (1991) ''vote-buying'' and Groseclose's (1995) ''favor-trading'' theories implies that significant cosponsorship and discharge-petition behavior will be concentrated in the middle of the ideological spectrum, independent of legislators' partisan affiliations. Hypotheses: Bill cosponsorship should be a primarily preference-based phenomenon. Waffling-defined as bill cosponsorship but refusal to sign a discharge petition for the bill-should be negatively associated with preference extremity and unaffected, at the margin, by majority party membership. Methods: Probit analysis of individual-level data. Measures of legislators' preferences electoral margin, seniority, committee membership, and party are used to predict patterns of cosponsorship and waffling on the A to Z spending plan in the 103rd House of Representatives. Findings: Consistent with the adapted Snyder/Groseclose hypotheses, cosponsorship and waffling are explained primarily by preferences, somewhat by membership on money committees, and only slightly by partisanship.
