By skipping the events in California and Michigan, two states with larger and more diverse electorates than Iowa and South Carolina, as well as more delegates at stake to help win the nomination, Mr. Walker risks diminishing himself. Once a national front-runner, he increasingly looks like a regional candidate — hoping his Midwestern roots will win him Iowa — who is pursuing single-state strategies rather than projecting confidence across the country.

His advisers said his political message — “Wreak havoc on Washington,” inspired by his record of tax cuts and labor and education overhauls in Wisconsin — held broad appeal that would lead to victories in primaries and caucuses after Iowa and South Carolina. They said the travel changes this month were not a reflection of money troubles or weak fund-raising, though one adviser noted that Mr. Walker has had to spend more time at political events in Iowa and elsewhere than at fund-raisers.

Mr. Walker is likely to spend most if not all of January campaigning in Iowa before the caucuses, said this adviser, who spoke on the condition of anonymity to discuss campaign strategy. Mr. Walker is aiming to visit all 99 counties in Iowa before the caucuses as a way to build support among Republicans there, in the spirit of successful campaigns like Charles E. Grassley’s Senate runs and Rick Santorum’s presidential bid in 2012.

Kirsten Kukowski, a spokeswoman for Mr. Walker, confirmed that the Michigan and California speeches were off but did not attribute any great meaning to the cancellations. Mr. Walker will be in California on Wednesday night to participate in the Republican presidential debate; he had been scheduled to speak in Michigan on Friday and then be back in California on Saturday.