I can't even keep track of how many people I know have been laid off in the last month, and a few of them are already having trouble paying the mortgage:

Unemployment is now the cause of almost half of all foreclosures on conventional mortgages, raising concerns that mounting joblessness will stall any housing recovery and could cause more foreclosures next year.

The increase in unemployment as a cause is a significant shift from 2007, when foreclosures were primarily driven by the large number of homeowners who had taken on risky loans. Many were first-time home buyers or those who bought during the housing boom that ended in 2006.

Now, layoffs and the recession are playing the pivotal role in driving mortgage defaults. The 4.3 million people collecting unemployment is the most since 1974, the Labor Department says.

During the first half of the year, about 46% of the 90-day delinquencies on conventional, conforming loans were because of a loss of income, vs. 36% in 2006, according to mortgage giant Freddie Mac.

Job losses exacerbate the situation for homeowners with risky mortgages. "A subprime buyer is already more fragile, so when unemployment rises, foreclosures go up," says Freddie Mac spokesman Brad German.

Mounting joblessness is also affecting homeowners who may have traditional, 30-year conventional loans but are living paycheck to paycheck.

They tend to be more urban, lower- and middle-class blue-collar workers, says Rick Sharga of RealtyTrac.

"It's not going to be pretty," Sharga says. "You're going to see whole different regions of the country suffer."