Disclaimer. Don't rely on these old notes in lieu of reading the literature, but they can jog your memory. As a grad student long ago, my peers and I collaborated to write and exchange summaries of political science research. I posted them to a wiki-style website. "Wikisum" is now dead but archived here. I cannot vouch for these notes' accuracy, nor can I even say who wrote them. If you have more recent summaries to add to this collection, send them my way I guess. Sorry for the ads; they cover the costs of keeping this online.
Leighley. 1996. Group membership and the mobilization of political participation. Journal of Politics 58 (May): 447-63.
This short but (empirically) clever piece suggests that the sort of mobilization discussed by Olson (1965), Uhlaner, and Shachar/Nalebluff doesn't happen. Leighley uses data from a national study of associations--surveying both leaders and members. She examines both political (Republicans, NARAL) and nonpolitical organizations.
Membership in either type of organization (political or nonpolitical) increases "unintentional mobilization"--basically, Putnam's style of mobilization. People learn leadership and participation skills and then use them in politics.
Only political organizations attempt "intentional mobilization" (telling people to go vote). When members join the political organizations for purposive reasons (e.g. they join because they want to lobby for specific legal changes, or for some other beneit), then intentional motivation succeeds. When members join the political organizations for non-purposive reasons (such as solidary or selective incentives), mobilization does not work. (That selective and solidary incentives don't lead to mobilization undermines Olson's (1965) model of collective action--and many later models.)
We can't claim that leaders are activating their followers; instead, followers appear to activate their leaders. When followers join an organization for purposive goals, their leaders can mobilize them, but otherwise the leaders are weak.
Research on similar subjects