After making fighting income inequality an early focus of his second term, President Obama has largely abandoned talk of the subject this election year in a move that highlights the emerging debate within the Democratic Party over economic populism and its limits.

During the first half of this year, Obama shifted from income inequality to the more politically palatable theme of lifting the middle class, focusing on issues such as the minimum wage and the gender pay gap that are thought to resonate with a broader group of voters.

The pivot is striking for a president who identified inequality as one of his top concerns after his reelection, calling it “a fundamental threat to the American Dream, our way of life and what we stand for around the globe.”

The shift also underscores the ongoing dispute between the Democratic Party’s liberal and moderate wings over how to address inequality issues. Whereas the left takes a more combative tone, seeking to focus on the income gap and what it views as the harmful influence of big business and Wall Street, more centrist forces in the party favor an emphasis on less-divisive issues.

White House officials say the change in the president’s rhetoric was driven by a desire to focus not just on the problem — economic inequality — but also on solutions that could address it. Others close to the White House contend that the move is at least partly driven by Democratic polling that found that talking about income inequality does not register strongly with the American public and risks accusations of class warfare.

“It was clear in 2013 that income inequality was the top narrative for the White House, but they abruptly switched away from it,” said Jim Kessler, senior vice president for policy at Third Way, a centrist Democratic think tank that has advised the White House and Democrats to avoid excessive populism. “Income inequality seems like it’s on the back burner now — at least in terms of their rhetoric.”

The shift hints at a broader repositioning of Democratic messaging ahead of the midterm elections and, perhaps, the 2016 presidential race. House and Senate strategists and their pollsters have concluded that they should focus less on the wealth gap and more on emphasizing that all Americans should have economic “opportunity” to get ahead or a “fair shot.”

“Both the White House and the Senate agreed that the decline of middle-class incomes was the most serious issue we face in this country, but the focus had to be on how to get middle-class incomes up, rather than drive other people’s incomes down,” said Sen. Charles E. Schumer (N.Y.), the messaging chief for Senate Democrats.

He added, “There are some who believe it’s better to talk about the negative parts of wealth that people have accumulated, but our polling data show people care less about that and more about how we’re going to help them.”

But many liberal Democrats, represented most prominently by Sen. Elizabeth Warren (Mass.), have been pushing an increasingly populist economic agenda. Some warn against papering over the wealth gap with euphemisms.

“It matters a lot, and I think that talking about inequality is talking about raising the bottom in a very concrete way for everybody, whereas talking about opportunity is much more narrowly focused,” said John Schmitt, an economist with the liberal Center for Economic and Policy Research.

The new Democratic focus, he said, risks being solely “about creating opportunities for some of the people at the bottom to go up, but leaving the rest of the folks where they are.”

Last year, Obama personally felt the pull of these arguments. White House political research showed that income inequality was a wonky term that did not always resonate with voters, but he insisted on speaking about it anyway.

That focus culminated in a December speech in a low-income neighborhood in Southeast Washington, where he referenced inequality 26 times and discussed academic findings on the gap between the wealthy and the poor.

“He wasn’t particularly interested in knowing whether that was a good economic message,” said one person familiar with the process, who spoke on the condition of anonymity in order to discuss private conversations. “He wanted to sound alarm and put voice behind that.”

But as 2014 loomed, White House strategists concluded that inequality was not registering with voters on its own.

A senior White House official, who spoke on the condition of anonymity in order to discuss private conversations, said that Obama primarily wanted to focus on more inclusive language such as “opportunity” and specific policies such as raising the minimum wage or infrastructure spending to create jobs that could help workers.

“Income inequality is much more a term of art than a term of everyday politics, and public-opinion polling has borne that out pretty quickly,” said Geoff Garin, a Democratic pollster. “I think it doesn’t have a personal immediacy and there are lot of other things that speak to income inequality that are much more immediate and much more tangible and much more real to people.”

Regardless of the terms he used, congressional Republicans have continued to lash out at Obama’s economic philosophy.

“As we head into the Independence Day weekend, it’s disappointing to realize that millions of our fellow Americans think the American Dream is slipping away because they can’t find good jobs in the Obama economy,” Republican National Committee Chairman Reince Priebus said Thursday.

Other conservatives, however, see room for agreement between Obama’s focus on mobility and Republicans, who have also been searching for better ways to address middle-class anxieties.

“I think it actually reflects not necessarily a consensus, but a growing recognition that there is a distinction between inequality itself and a deeper concern about whether there are some people who lack the ability to move up the economic ladder,” said Stuart Butler, a senior fellow at the conservative Heritage Foundation.

Meanwhile, other left-leaning economists say it does not matter whether Obama chooses different language so long as he advocates the right policies.

“When I hear inequality and middle class, they are two slices of the same thing,” said Heather Boushey, executive director of the Washington Center for Equitable Growth. “Politically, his job is to connect with his constituents in trying to figure out which of those phrases are the most compelling.”

Beyond the politics, Obama’s public statements suggest he is skeptical that members of either party would embrace some of the policies aimed squarely at reducing income inequality, such as taxing wealthier Americans in order to give more benefits to poorer Americans.

In a profile this year, Obama told David Remnick of the New Yorker that “the appetite for tax-and-transfer strategies, even among Democrats, much less among independents or Republicans, is probably somewhat limited, because people are seeing their incomes haven’t gone up, their wages haven’t gone up. It’s natural for them to think, ‘Any new taxes may be going to somebody else, I’m not confident in terms of how it’s going to be spent, I’d much rather hang on to what I’ve got.’ ”