Commercials for fast food hamburgers are ubiquitous on television, but French fries don’t get nearly as much love.

On Monday, however, Wendy’s will announce the details of a national marketing plan for its new recipe for French fries, the biggest overhaul of its fries in 41 years. “Fries,” said Ken Calwell, the chief marketing officer at Wendy’s, “is something we hadn’t been a leader in, in the past.”

For the last year, the company has been examining its product line for opportunities to promote food made with more natural ingredients, Mr. Calwell said. Wendy’s “new natural-cut fries with sea salt” use Russet Burbank potatoes and are thinner and crisper than the current fries and will be unpeeled.

The idea is to provide an alternative to McDonald’s, which has long been the leader in French fry sales. The Wendy’s campaign, which begins on Nov. 29, includes two television spots that will run on cable and network stations like TBS, VH1 and Bravo and during shows like “Conan” and “Lopez Tonight.” The cost of the campaign is estimated to be $25 million.