During Reagan’s years in office, unemployment and inflation dropped sharply. Tax rates generally fell, as did spending on government programs outside the military. But there were also two significant downsides to the 1980s economy, and Mr. McCain has made an issue of both at different points in his career. The budget deficit soared, because the cuts in domestic spending were not large enough to make up for the Reagan tax cuts and a military buildup. And middle-class incomes grew at a much slower rate than they had in the 1950s or ’60s.

In the aftermath of his loss to Mr. Bush in the 2000 Republican primaries, Mr. McCain began emphasizing middle-class pocketbook issues. After having consistently voted for tax cuts in the 1980s, he was one of the few Republicans to oppose the administration’s tax cuts in 2001 and 2003. He said at the time that they benefited “the most fortunate among us at the expense of middle-class Americans.”

In the current decade, wage gains for most families have been even weaker than they were in the 1980s, and Mr. McCain has spoken during the campaign about the anxiety being caused by a globalization and technological change. Were he to win the Republican nomination, it is possible he would then put a bigger emphasis on such themes.

“Change is hard,” he said in a speech in Detroit in October, “and while most of us gain, some industries, companies and workers are forced to struggle with very difficult choices.”

To spur the economy, Mr. McCain has called for more spending on alternative-energy research. Spending on basic research, he said, could lead to a repeat of the Internet’s success story, in which government financing ultimately led to the creation of a huge private industry. He has also called for an expansion of community-college programs and an overhaul of unemployment benefits, to reflect the fact that people who lose their jobs now are often out of work for long periods.

Mr. McCain now favors the extension of the Bush income tax cuts, saying that letting them lapse would amount to a tax increase that would damage the economy. He said the Democrats’ plans to allow the expiration of the Bush tax cuts for households making at least $250,000 would simply redistribute wealth and lead to an endless fight over who was truly affluent.

“Americans don’t dislike wealthy people; they want to be wealthy people,” he added.

On several occasions over the last year, Mr. McCain has said that tax cuts can reduce the deficit by spurring additional activity that, in turn, leads to more taxes being paid. But numerous studies have found that not to be the case.