SOUTH BEND, Ind. — When Tom Grimes lost his job as a financial consultant 15 months ago, he called his congressman, a Democrat, for help getting government health care.

Then he found a new full-time occupation: Tea Party activist.

In the last year, he has organized a local group and a statewide coalition, and even started a “bus czar” Web site to marshal protesters to Washington on short notice. This month, he mobilized 200 other Tea Party activists to go to the local office of the same congressman to protest what he sees as the government’s takeover of health care.

Mr. Grimes is one of many Tea Party members jolted into action by economic distress. At rallies, gatherings and training sessions in recent months, activists often tell a similar story in interviews: they had lost their jobs, or perhaps watched their homes plummet in value, and they found common cause in the Tea Party’s fight for lower taxes and smaller government.

The Great Depression, too, mobilized many middle-class people who had fallen on hard times. Though, as Michael Kazin, the author of “The Populist Persuasion,” notes, they tended to push for more government involvement. The Tea Party vehemently wants less — though a number of its members acknowledge that they are relying on government programs for help.