As has been widely reported, retail sales in November were slower than expected. According to the International Council of Shopping Centers (ICSC), its most recent survey of 70 retailers (released yesterday) indicates that comparable-store sales increased only 1.7% overall, below its November projection of between 2.5% to 3%, which had already been revised down from between 3% to 4% initially.

Higher-end retailers such as Nordstrom (NYSE:JWN) and Neiman Marcus (NYSE:NMG.A) had a solid month -- ICSC's luxury sector gained 5% for the month. In contrast, the middle market department store sector, which includes companies such as Federated (NYSE:FD) and May (NYSE:MAY), came in at 2%, and the discount sector, with companies such as Wal-Mart (NYSE:WMT) and Target (NYSE:TGT), struggled with only a 1% gain.

The last time retail numbers were this soft was last summer. At that time, I wrote a detailed piece about the deteriorating balance sheet of the U.S. consumer. I still firmly believe that consumers are stretched too thin financially and that consumer spending will ultimately have to slow significantly.

The fact that the low-end sector had the slowest growth in November concerns me. It indicates that lower-income Americans are feeling real financial pressure, as the impact of rising interest rates is added to sustained high gasoline prices, while jobs are not being created quickly enough and wages are not rising fast enough to compensate for higher expenses.

The next couple of months will be critical to determine whether this is just a bump in the road (as last summer was) and consumer spending will remain strong for the foreseeable future, or whether this is the beginning of a sustained slowdown in consumer spending. The key question for me is whether inflation and interest rates will rise faster than employment and wages do.

If they do, I think we could see a dramatic and prolonged slowdown in consumer spending, particularly if higher interest rates result in a cooling off of the real estate market. Consumer spending accounts for two-thirds of the economy, and a significant slowdown could easily send the U.S. economy back into a recession.

This morning's jobs report indicates that the recovery is still very much at risk, but I've certainly been wrong on this issue before -- the resiliency of consumers to keep borrowing and spending has astonished me. That being said, I also think that the longer the binge goes on, the more painful the inevitable hangover will be.

Fool contributor Salim Haji lives in Denver and does not own any of the stocks mentioned in this article.