A top strategist for Mitt Romney conceded Monday that the campaign has not provided enough specifics about the candidate’s vision for the country and pledged a renewed effort in the last 50 days of the race to better communicate with voters.

Ed Gillespie, a veteran Republican operative who is advising Mr. Romney, told reporters that voters were demanding more specifics from the campaign on the economy, foreign policy and energy concerns. He said the revamped approach will focus on communicating better about the candidate’s existing ideas rather than providing new ones.

“We are not rolling out new policy,” Mr. Gillespie said, “so much as we are making sure people understand that when we say we can do these things, here’s how we are going to get them done and these are the specifics.”

For months, Mr. Romney’s central strategy has been to attack President Obama‘s leadership and his handling of the economy. Aides have long said they believe the campaign will be a referendum by voters on their dissatisfaction with the president and the direction of the faltering economy.

But Mr. Gillespie said that recent polling done by the campaign suggested that voters were increasingly tuning into the campaign now and were eager to hear more from Mr. Romney about his own plans.

“What we have found is that people want to hear a little more of that,” Mr. Gillespie said. “We think there’s a demand out there.”

The shift in approach comes amid increasing criticism from Republicans outside the campaign and polls showing Mr. Romney slipping in key swing states. An article in Politico Sunday night detailed carping among Mr. Romney’s campaign advisers about who is to blame, with much of the finger-pointing aimed at Stuart Stevens, the top strategist for the campaign.

Conservative supporters of Mr. Romney’s campaign have increasingly voiced concern that the campaign has been too vague in its promises to voters and risks offering a bland alternative that will not succeed in November.

William Kristol, the editor of The Weekly Standard, wrote last week that Mr. Romney must “speak up” on the specifics that would animate his presidency or risk losing.

“When a challenger merely appeals to disappointment with the incumbent and tries to reassure voters he’s not too bad an alternative, that isn’t generally a formula for victory,” Mr. Kristol wrote. “Mike Dukakis lost.”

John Podhoretz, a conservative commentator, wrote in The New York Post that: “Romney & Co. are wrong if they think negative feelings toward Obama are sufficient to motivate their voters. These people would like very much to believe in their candidate. That’s not happening now.”

Mr. Gillespie did not directly address Mr. Stevens or the late-in-the-game campaign squabbling inside and outside of the Boston headquarters. And he said the timing of the change in strategy was partly a natural evolution now that the election is drawing near and more voters are paying attention.

But he made clear that the campaign views the coming period as the time for a “new emphasis and renewed emphasis” on Mr. Romney’s approach to governing.

As examples, Mr. Gillespie said that in a speech in California Monday, Mr. Romney would highlight previous proposals to limit the growth in federal programs and reduce the federal work force that will reduce spending by $500 billion in four years. The speech will be before the United States Hispanic Chamber of Commerce in Los Angeles.

Asked for examples of other specifics, Mr. Gillespie said the campaign would underscore its promise to be energy independent by the year 2020 by repeating Mr. Romney’s pledge to approve the Keystone oil pipeline, allow drilling off the coast of Virginia and lift the moratorium on oil exploration in the Gulf of Mexico.

“The timing is right at this moment to reinforce the specifics,” Mr. Gillespie said.

The approach will involve new stump speeches by Mr. Romney and his running mate, Representative Paul D. Ryan of Wisconsin, Mr. Gillespie said.

In Los Angeles on Monday, Mr. Romney did not deliver an entirely new speech, but it had a different emphasis. The candidate, who usually

devotes much of his standard stump speech to a lengthy indictment of Mr. Obama’s record, instead focused heavily on his plans to

eliminate government spending in Los Angeles. He outlined his proposal to cut federal subsidies for Amtrak, the Corporation for Public

Broadcasting, the Legal Services Corporation and the National Endowments for the Arts and Humanities. (The ideas are not new for Mr.

Romney, but they rarely make their way into his remarks.)

However Mr. Romney still withheld many key details. When explaining his plan to reduce the size of the federal government by $500 billion

a year, he vowed to cut employment by 10 percent through attrition and eliminate or combine agencies, but did not say how many or identify

which.

Sounding a familiar theme, Mr. Romney declared that “the President has put us on the road to Greece. I will put us back on the road to a

stronger America, one which stops spending more than we take in.”

In his conference call with reporters, Mr. Gillespie said the new approach would also involve background papers and new ads, some of which began running on Monday.

In one new ad the campaign released Monday morning, Mr. Romney promises he would make a stronger middle class by improving foreign trade with a “crackdown on cheaters like China” and cutting the federal deficit.

“You’ve got to stop spending more money than we take in,” Mr. Romney says in the ad, which does not mention or directly criticize Mr. Obama. In the ad, called “The Romney Plan,” Mr. Romney also pledges to create 12 million new jobs with a focus on small business.

That ad, and another emphasizing the growth in the nation’s debt, are intended to make the case for Mr. Romney taking over in the White House.

A spokeswoman for Mr. Obama’s campaign said the ads would not convince voters that Mr. Romney’s prescriptions for the country are better than the ones that Mr. Obama has been following for the past several years.

“The American people have no reason to believe Mitt Romney would reduce the deficit or strengthen the middle class – it’s not what he did as governor and it’s not what he’s proposing to do as president,” said Lis Smith, a spokeswoman for the Obama campaign.

After the speech in Los Angeles on Monday afternoon, Mr. Romney’s campaign schedule remains light for the rest of the week. There is a planned fund-raiser in Los Angeles Monday night, and Mr. Romney has no public events on Tuesday. He is scheduled to have only a single public event on each day later in the week, though the campaign could still add events.

On Sunday, Mr. Romney had planned an event in Colorado, a critical swing state where Republicans had hoped to deny the president a repeat victory. But a small plane crash at the airport where Mr. Romney was scheduled to land forced the event to be canceled.

Michael Barbaro contributed reporting.