WASHINGTON — Trailing in the polls 50 days before the election, Republican White House challenger Mitt Romney dismissed Monday charges his campaign was in disarray and said there would be no shake-up.

"I've got a terrific campaign," he said in an interview with Telemundo to air on Monday night. "My senior campaign people work extraordinarily well together. I work well with them. Our campaign is doing well."

Since the party conventions two and three weeks ago, President Barack Obama has put some daylight between himself and Romney and opinion polls now show him ahead both nationally and in several key battleground states.

With parts of the US media prematurely readying his political obituary, Romney is facing increasing calls from fellow Republicans to flesh out his economic policies or risk slipping further behind his rival.

Voters are "eager to hear more details about policies," senior Romney adviser Ed Gillespie acknowledged on Monday as he indicated that more concrete plans would be unveiled at campaign appearances in the coming week.

While Romney and running mate Paul Ryan would not be "rolling out new policy" this week, they will "reinforce more specifics about the Romney plan for a stronger middle class," Gillespie said.

Romney pivoted back to the economy on Monday, releasing two new television ads in swing states as he returned to his familiar role of hammering Obama for failing to turn things around since the 2008 financial crisis.

"My plan is to help the middle class," the Republican nominee says in one, adding: "we can't keep buying and spending and passing on debts to our kids."

For months Romney has sounded the alarm about the ballooning debt and budget deficit under the Obama presidency, but two recent polls suggest he may be losing his long-held advantage as the more popular economic manager.

That is unexpectedly sour news for a candidate who last month rolled out budget hawk Ryan as his VP pick in a move his campaign had hoped would boost his credibility, especially with fiscal conservatives.

Voters are anxious as a "fiscal cliff" confronts the nation next January, when Bush-era tax breaks are set to expire and automatic spending cuts kick in if a divided Congress cannot reach a deal.

An explosive behind-the-scenes report by Politico late Sunday offered little comfort to concerned conservatives, as it depicted a campaign -- and a candidate -- fumbling opportunities to present Romney in the best light, such as his speech to the Republican convention in Tampa last month.

The report focused on how chief strategist Stuart Stevens morphed from Romney's top advisor to the major scapegoat for the team's series of missteps.

Romney, a multimillionaire investor and former governor of Massachusetts, had drawn neck and neck with Obama during the summer campaign season, but with just 50 days to go until the November 6 election, polls show the challenger trailing.

Politico dissected Romney's campaign battle strategy, laying out how the candidate put his faith for the most part in an impulsive advisor who has ended up serving three crucial roles himself: top strategist, ad maker and speechwriter.

It said Stevens scrapped two early versions of Romney's Republican convention speech in Tampa, bypassing the campaign's speechwriters in Boston and writing much of it himself.

The speech was seen as helping to humanize Romney, but it lacked key elements such as a salute to US troops or any mention of Al-Qaeda or Afghanistan.

Romney received no substantial boost from the convention, and some conservatives ripped the campaign for allowing Hollywood icon Clint Eastwood to ramble on about Obama -- an act which Stevens reportedly greenlighted -- minutes before the most important speech of Romney's life.

Stevens defended the campaign's performance.

"Like all campaigns, we have good days and bad days. I'm happy to take responsibility for the bad days," he told Politico, adding that Romney was doing better than many pundits have been saying.

But the article cited sources close to Romney as saying the blame cannot be pinned entirely on Stevens, and that Romney bears responsibility for decisions he personally oversaw.

"Romney associates are baffled that such a successful corporate leader has created a team with so few lines of authority or accountability," the report said.