As ugly as the holidays were for retailers, the next few months aren't going to be much better, according to a forecast released Tuesday by the National Retail Federation.

Retail sales for all of 2009 will slide 0.5 percent, with the strongest decline happening in the first half of the year, when sales are expected to plummet 2.5 percent.

There will be a slight moderation in the third quarter, when sales decrease just 1.1 percent, and fourth-quarter sales will jump 3.6 percent based on easy comparisons with last year.

"Most of the consumer behavior we saw in 2008 will continue well into this year," NRF chief economist Rosalind Wells said in a statement. "Shoppers will be seeking value and trading down to discount and off-price retailers in order to stretch their purchasing power."

The NRF, a Washington- based trade group, excludes automobiles, gas stations and restaurants from its definition of retailers.