Almost $80 million is spent on TV ads for Georgia's 4-week Senate runoff

This photo composite shows Democratic Georgia Sen. Raphael Warnock, left, and his Republican challenger, Herschel Walker. The two are competing in a U.S. Senate runoff, which concludes Tuesday. (AP)

There has been a rush of spending on TV ads for the pivotal Georgia U.S. Senate runoff, which is just a shortened four-week campaign.

In that period, some $79 million has been poured in to buy airtime. And spending by groups supporting Democratic incumbent Sen. Raphael Warnock has more than doubled contributions from groups backing Republican challenger Herschel Walker, according to data from the ad-tracking firm AdImpact and analyzed by NPR.