About two-thirds of the public now believes there are strong conflicts between the rich and poor in America, making class a likelier source of tension than traditional flash points of race or nationality, a study from the Pew Research Center found.

The nonprofit think tank in Washington released a study Wednesday that reported a growing number of Americans say there are “very strong” or “strong” conflicts between the rich and poor — a number that has risen by 9 percent since July 2009.

“It is kind of amazing,” said Richard Morin, a senior editor at Pew who authored the study. “This is people not only sensing conflict, but people sensing an intensity of these conflicts — that’s what makes it striking and politically important.”

This pronounced attitude shift occurred throughout the income spectrum — from the very poor to the wealthy — as well as among those with diverse political views. But younger adults, Democrats and African Americans were more likely than others to sense the class tension, according to the study, a national survey of 2,048 adults.

Morin wrote that this marked attitude change in a short period of time probably reflects the message of the Occupy Wall Street movement but also a growing public awareness of the shifts in wealth distribution in America. In recent years, the top 1 percent of earners have seen their fortunes rise while lower incomes have stagnated, and the top 1 percent now controls more than a third of the wealth.

“I think you see very, very rich people, and there is a jealousy there by the people on the other end, the poor side. . . . It’s worse than it’s ever been,” said Ira Ellis, 64, a retired professional photographer from Las Vegas who participated in the study. In his community, he sees everything from mega-high-rollers to rising ranks of homeless people because of his state’s high foreclosure rates.

The class divide is expected to be a major theme in the 2012 presidential campaign. President Obama preached a return to middle-class values in a speech last month, and conservative Republicans are fretting about the possibility that class warfare will be Topic A in the general election.

Morin wrote that although Americans are more aware of this significant shift in class in America, it does not necessarily signal an “increase in grievances toward the wealthy.” As many as 43 percent believe that the rich become so because of their own hard work, ambition or education, the study showed, compared with 46 percent who believe that the wealthy become rich through connections or birth.

And these attitudes seem to be shared regardless of income level. Nearly 67 percent of adults with a household income of less than $20,000 a year believe there are serious conflicts between the rich and poor, as do 67 percent of those earning $75,000 a year or more, Morin wrote.