This report on the attitudes and lives of the American middle class combines results of a new Pew Research Center national public opinion survey with the center's analysis of relevant economic and demographic trend data from the Census Bureau. Among its key findings:

Fewer Americans now than at any time in the past half century believe they're moving forward in life.

For decades, middle-income Americans had been making absolute progress while enduring relative decline. But since 1999, they have not made economic gains.

About half of all Americans think of themselves as middle class. They are a varied lot.

For the past two decades middle-income Americans have been spending more and borrowing more. Housing has been the key driver of both trends.

At a time when these borrow-and-spend habits have spread, Americans say it has become harder to sustain a middle-class lifestyle.

Economic, demographic, technological and sociological changes since 1970 have moved some groups up the income ladder and pushed others down.

Most middle class adults agree with the old saw that the Republican Party favors the rich while the Democratic Party favors the middle class and the poor.