If the lovely village of Fox Lake was a perfect hideout for Al Capone, it was also a fitting hangout Sunday for Joe Walsh, a law-abiding political provocateur, and provided a window onto a creeping long-term peril for Republicans.

Mr. Walsh, 49, is a freshman Tea Party congressman whose public meetings, like the one in G.O.P.-leaning McHenry County, rival “Law and Order” reruns in frequency as he presses a simple and unsettling agenda: cut, cut, cut government spending.

“We’ve got a government we can’t afford, and we’re broke!” he declared with brio to a good turnout of 125 in Lakefront Park on a recent gorgeous afternoon.

He work khaki pants and a pale purple-and-white striped, open-collared dress shirt while he talked about the improbable issue of the day: raising the debt ceiling.

“They sent us to Congress to stop what this president’s doing and all this government spending,” he said before holding a vote in which his mostly older audience preferred that an increase in the debt ceiling be accompanied only by budget cuts, not tax increases.

But while Mr. Walsh got grief from two attendees of Democratic persuasion, more notable were the declarations, and qualms, of his supporters.

They spoke of President Obama “killing our country,” immigrants ruining the country, a secret cabal now running all government (“I read it on the Internet”) and ending foreign aid.

Meanwhile, Sheila Conners, the part-time clerk of Richmond Township and a laid-off newspaper computer support specialist, fretted that Mr. Walsh, whom she loves “for sticking to his guns,” could get too doctrinaire. On the debt ceiling, she said, “both sides have to give on this,” including taxing the wealthy and corporations.

The half-baked and anxious rumblings suggest how a moment of great strength for the conservative movement might contain seeds of its decline.

This period may be a counterpoint to the intellectual ferment of the 1960s and ’70s. Liberal notions of social justice, environmentalism, less intrusive government and warding off nuclear destruction morphed into Democratic orthodoxies and inspired a conservative revolution that led to Ronald Reagan.

The recent conservative flowering encompasses pretty sensible notions, including how we should integrate free market ideals with commensurate government involvement and incentives. But it might morph into an inflexible ideology that is too harsh, naïve about the downsides of free markets and not where most Americans want to wind up.

Might next year’s critical swing voters end up seeing the Hard Right as a Ridiculous Right?

Mr. Walsh will be an engaging tidy test case and not just because a Democratic-controlled redistricting may force him to run in a primary against another G.O.P. incumbent — or because his ex-wife is suing for child support he asserts he does not owe.

He worked hard last year to pull a primary upset and then upend Melissa Bean, an incumbent Democrat. He has stuck to his guns in Washington and not compromised in ways that some would deem necessary but others might see as selling out.

When he has voted against the Republican majority — for greater military cuts and trimming agricultural subsidies to individuals — it’s because he thinks the cuts don’t go far enough. And that’s why many voters in the Eighth District sent him to Washington.

But there’s the risk of caricature, especially by the news media. Some of his comments, like calling Mr. Obama a liar, have helped make him a presence on cable television, including a raucous “Hardball” appearance where the hosts, Chris Matthews, argued that Mr. Walsh was dishonest in not being specific on where we should cut spending.

He has generally acquitted himself well even while opening himself to sound-bite mockery as opponents edit comments and e-mail the results.

Throughout, he seems undaunted as he hustles about his district and displays a congenial knack for retail politics. He even warned supporters Sunday against getting their news from a single source, be it Fox News Channel, MSNBC, The New York Timess or The Wall Street Journal.

Still, beware of any leaf inspiring a political movement. If liberals smoked too muchmarijuana, conservatives may wind up drinking a bit too much tea.