Iowa doesn’t pick presidents, it simply winnows the field. It’s too prosperous to provide an adequate test of which GOP candidates can prevail in more economically challenged primary states and the general election.

With New Hampshire also prosperous and fairly safe for Mr. Romney, the South Carolina and Florida primaries on January 21 and 31 offer him the opportunities to prove he has what it takes to solve the country’s problems and score convincing victories.

In both those states, unemployment is 10 percent, as opposed to less than 6 percent in Iowa and New Hampshire. Mr. Romney must do more than chant the Republican catechism—less taxes, less government and less regulation—because all the candidates are doing the same in one fashion or another. He must explain to voters what’s broken—how Mr. Obama’s policies are holding back growth and jobs creation—and outline how he will fix those things.

Moreover, after George W. Bush bequeathed to President Obama a U.S. economy in dire straights, in the general election, the Republican nominee cannot simply fall back on the catechism without becoming too vulnerable to Mr. Obama’s claim that all the Republicans care about is enriching the rich and returning failed policies of the past.

In Iowa, amid all the discussion, there was not enough focus on the economy. Iowa caucus-goers divided between 25 percent who picked Mr. Romney because he is perceived to be “most electable,” and 75 percent who splintered among a flock of other candidates who fashioned themselves “true conservatives.”

Each offered their own flavor of conservatism, and Rick Santorum—the least vetted and vulnerable—essentially tied Romney.

Romney demonstrated considerable strength among voters earning more than $100,000 a year, and the candidate with the most unrealistic and maddening platform, Ron Paul, finished a strong third by drawing significant support from those earning less than $50,000.

Therein lies Mr. Romney’s challenge—folks earning more than $100,000 don’t need a better economy nearly as much those gravitating to Mr. Paul’s bizarre prescriptions, which includes shutting down the Federal Reserve and returning to the gold standard.

Mr. Romney has a solid platform. Unlike President Obama, he understands nothing is much wrong with what Americans can do and make, but unbalanced trade with China and costly imported oil are sapping too much demand—sending too many consumer dollars abroad to pay for imports that don’t return to purchase U.S. exports, and slowing growth.

And high health care costs, and new financial regulations that don’t curb bank abuses but have shut down lending for most business expansion, make investing and creating jobs in America too difficult and expensive.

Mr. Romney’s principal challenges are that too many primary voters who pick the Republican nominee like simple conservative orthodoxy—get the government out of my life—but moderates who made Mr. Obama president and Mr. Romney must win over in November don’t drink that Kool Aid.

Furthermore, conservative pundits, such as editorial writers at the Wall Street Journal and George Will, endlessly ridicule Mr. Romney’s economic program for having 59 points instead of three—lower taxes, less government and deregulation—and are denying him an honest assessment from analysts who should be sympathetic toward his quest for the presidency.

As things stand, Mr. Romney, in the general election, would have to contend with both Democrats in the media sympathetic toward Mr. Obama’s big government philosophy, and Republicans in the media who think too much like Republican primary voters and can’t accept that something more nuanced than conservative orthodoxy is needed to right the country.

To turn his 25 percent plurality in Iowa into convincing wins in South Carolina and Florida, and beat Mr. Obama in November, Mr. Romney must concisely and accessibly explain how Mr. Obama’s passive response to Chinese protectionism, limits on oil and gas development, expensive health care mandates, and quagmire of bank regulations are strangling American capitalism.

And then... he must tell Americans how his program can quickly turn things around.

Mr. Romney's 59 points already include most of the nuts and bolts to do just that, but now it is time for the executive summary and eloquent delivery.

It will take skill for him to convince voters and courage for Mr. Romney to recognize that simply berating Washington is not enough to win the election. The world is too complex for the government of Rutherford B. Hayes, but surely safe enough for an America that relies on entrepreneurism and accountability, and not command and control, to prosper and grow.

Peter Morici is a professor at the Smith School of Business at the University of Maryland and former chief economist at the U.S. International Trade Commission. Follow him on Twitter@pmorici1.