One reason the activists are angry with the Republican senatorial committee is that it is holding fund-raisers for Mr. Hatch — they waved signs reading “Retire Hatch.” But more generally, they want the committee to withhold political or financial support from any incumbents in the primary.

“It’s like they haven’t learned the lessons of the midterms,” said Brendan Steinhauser, an organizer for FreedomWorks who urged on the marchers…

“We respect their views just as we respect the views of others who are strongly supporting Senator Hatch’s re-election, including Mark Levin and C. Boyden Gray, who is the co-chairman of the FreedomWorks Foundation Board,” said Mr. Walsh. Mr. Levin is a conservative radio talk show host, and Mr. Gray a former diplomat and counsel to President George H.W. Bush.