In a shift over a half-century, the party base has been transplanted from the industrial Northeast and urban centers to become rooted in the South and West, in towns and rural areas. In turn, Republicans are electing more populist, antitax and antigovernment conservatives who are less supportive — and even suspicious — of appeals from big business.

Big business, many Republicans believe, is often complicit with big government on taxes, spending and even regulations, to protect industry tax breaks and subsidies — “corporate welfare,” in their view.

“One of the biggest lies in politics is the lie that Republicans are the party of big business,” Ted Cruz, a new senator from Texas and a Tea Party favorite, told The Wall Street Journal during his 2012 campaign. “Big business does great with big government. Big business is very happy to climb in bed with big government. Republicans are and should be the party of small business and of entrepreneurs.”

The tension, so evident last month in the tax fight over the fiscal deadline, is apparent again as Mr. Obama and a new Congress contend over the even more pressing need to increase the nation’s debt limit next month.