A new survey shows that Americans are generally taking a dimmer view of homeownership, even as a rising number say they believe it’s a good time to buy a home.

The survey from Fannie Mae reveals lots of interesting insights like this one: homeowners who are underwater, or owe more than their homes are worth, are more likely to view housing as a safe investment than renters. Almost three out of four mortgage borrowers, and nearly seven in ten underwater homeowners, say that housing is safe, compared to just 57% of delinquent borrowers and 54% of renters.

Overall, the number of Americans who say that homeownership is a safe investment has declined—to 67% in July, from 70% in January and 83% in 2003.

While more people believe that it’s a good time to buy and a bad time to sell, the number of Americans who say they’re likely to rent, rather than buy, their next house has increased slightly since January, to one third of those surveyed. (Columnist Brett Arends offers his list of 10 reasons to buy.) Respondents also expect rents to grow much faster than home prices over the next year.

The report shows some worrying trends for banks and mortgage investors. While three-quarters of borrowers consider their mortgage payment to be their most important debt obligation (that hasn’t changed since January), the number of delinquent borrowers that count their mortgage payment as their most important has fallen, to 50% in July from 57% in January.

The vast majority of Americans still disapprove of borrowers stopping their mortgage payments. But the number who say it’s acceptable to default if a borrower is underwater has increased slightly, to 10% from 8% in January.

A few other findings from Fannie’s survey (view the full results, in pdf):

• Nearly half of all borrowers, and more than half of underwater borrowers, think their lender is likely to pursue other assets in addition to their homes if they were to stop paying their mortgage. [The ability of the lender to do this actually varies from state to state.]
• Underwater and delinquent borrowers are also slightly more optimistic about the amount of time it will take for their credit scores to recover after a mortgage default. Around one in five of those borrowers say that it would take one to three years to wipe a mortgage default from their credit report, compared to one in seven for the general population.
• A majority of Americans also believe that borrowers are more at fault than mortgage companies for having unaffordable loans. Nearly 56% of borrowers—and 60% of underwater borrowers—say that borrowers, not banks, have greater culpability for being in over their heads with respect to affordability.

A separate survey from the Pew Research Center found that 19% of those polled said it was acceptable to walk away from a mortgage, while 59% said it was unacceptable and 17% said it depended on the situation.

Democrats were twice as likely to say that it was acceptable to walk away from a mortgage (23%) than Republicans (11%), according to the Pew report.

Follow Nick on Twitter for more housing and mortgage news: @NickTimiraos