But one professional ad tracker says Sanders’ ads, which have all cast the senator in a positive light, have not yet paid off.
“Those seeking evidence that TV ads aren’t having their typical impact this time around will find it twofold in the fact that Sanders’ ads don’t seem to be moving his numbers, after his numbers initially surged without any ads at all,” said Elizabeth Wilner, the senior vice president of Kantar Media who oversees its Campaign Media Analysis Group.
Overall, the Sanders campaign raised about $73 million in 2015, mostly from people contributing $200 or less. The Clinton campaign raised $112 million during that time — the bulk of which has come from people giving $1,000 or more.
“We do have the resources to wage a very serious campaign,” Briggs said, who also noted the campaign recently surpassed one million individual campaign donors.
Representatives of the Clinton campaign did not respond to requests for comment.
At this stage of the 2008 presidential campaign, Clinton had raised $118 million, while Barack Obama had raised about $104 million.
Clinton has also been buoyed by a network of super PACs, which can collect contributions of unlimited amounts.
So far, these groups — the most prominent of which is known as Priorities USA Action — have largely stayed off the TV airwaves. But they certainly have the resources to pound the Sanders campaign with incessant negative ads should they so choose.
Sanders has disavowed super PACs, although one super PAC connected to a nurses’ union has spent more than $800,000 on his behalf. The bulk of that money has supported printing costs and a pro-Sanders bus tour, not TV ads.
This story was co-published with TIME and Al Jazeera America.