"The Following" is one of Fox's few success stories this season (Twitter)

Despite eight consecutive seasons as the number one network among viewers aged 18-49, Fox’s ratings continue to decline. CBS, who consistently surpasses Fox in total viewership, looks poised to steal the throne. The race for first gets tighter and tighter every year, and CBS is having an atypically strong season at a time when Fox is lagging.

The bulk of Fox’s trouble stems from the failures of their new shows. “The Following” proved to be a midseason success, but both “Ben and Kate” and “The Mob Doctor” have already been cancelled. Its “New Girl” lead-in is the only think keeping “The Mindy Project” breathing, and Fox’s other new comedy, “The Goodwin Games,” has been pushed back to air in the summer with a drastically cut episode order, signaling serious trouble.

Even old standbys for Fox aren’t what they used to be. This season of the juggernaut “American Idol” premiered with the lowest numbers since its debut in the summer of 2002 and has since sunk to series' lows in the past few weeks. Once reliable to beat any competition, the show was topped by “NCIS” in total viewers and ABC’s “Modern Family” in the coveted young adult demographic earlier this year. Neither “American Idol” nor “The X Factor” have been able to match the success of “The Voice,” a strong performer that helped propel NBC to number one in late 2012.

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CBS, on the other hand, has only been growing. The network won its first February sweeps in fifteen years with the help of The Super Bowl and The Grammys. “The Big Bang Theory,” one of the few thriving sitcoms on the air, drew series-high ratings in January 2013, the middle of its sixth season. Regularly outpacing “Idol’s” Thursday night results shows, it is a strong possibility that “The Big Bang Theory” will usurp “American Idol” as top show of the season.

Fox may have to give up its number one spot at the end of the season, but it will likely do better than the floundering NBC. With two of its strongest performers, “The Voice” and “Revolution,” off the air, NBC fell to fifth place behind the Spanish-language network Univision in February sweeps.  During the same period “Smash”—which delivered promising ratings in its first season—plummeted 25% upon its return.

Network TV viewership is down across the board as more and more viewers watch their favorite shows online or by DVR. All of the networks are looking for new ways to encourage viewers to watch live, but CBS seems to be the only one succeeding. Live viewership is incredibly important to advertisers and with only a few months left in the 2012-13 season, Fox and the other networks have little time to turn themselves around and make their ad-time for next fall more appealing.

Reach staff reporter Reid Nakamura here.