The pressure is building for holiday.

Consumer behavior is the X factor, and if the recent past is any indication, shoppers will demand value and put off purchases on the expectation that stores will blink and cut prices.

Moody’s Investors Service said in a recent research note that department stores — even with inventories more in line with sales than during the depths of the recession a year ago and despite better than expected first-half earnings — are likely to beat the discount drum for holiday.

“We believe there is a high risk that the American consumer will have a ‘discount staring contest’ with the department stores by delaying purchases until they see a level of discounts that they believe offers them value,” the ratings agency said. “We believe that the department stores will likely blink first by opting to quickly mark down rather than risk having the inventory left over after the holiday season.”

Disappointing back-to-school sales were not a positive harbinger for holiday or the third quarter.

Although August same-store sales results were slightly better than in July, they weren’t sufficient to lift most third-quarter expectations. Consumers’ tentative shopping patterns and a late Labor Day shifted much of the burden for third-quarter sales into September.

Even with easier comparisons, signs of slowly improving consumer confidence and greater stability in the credit markets, the prospects for retail sales in the back end of the year are uncertain.

According to a Wedbush Morgan Web-based survey of 1,013 adults and 513 teens, 70 to 76 percent of b-t-s shopping had been completed by the end of August. The survey also indicated that b-t-s budgets contracted 22.6 percent to $342 in August from $442 in July.

This was significant because many expected “a back-end-loaded back-to-school season,” as Labor Day shifted to the second week of September and schools opened later, said Wedbush Morgan retail analyst Betty Chen.

“Not only is spending down, but about 70 percent of spending had already been done in August,” she said. “Knowing this, we are more worried.”

If September same-store sales do not improve over August’s results, investors could “reassess a potential fourth-quarter turnaround,” Chen said. This will only add to the pressure, both on Wall Street and at the mall, to pull the promotional trigger.