So far the candidates running in the 2020 election for the Democrats have spent over $450 million in advertising.  This is proving to be a windfall for local broadcasters in the US. Most of the money has been spent on television.

Mike Bloomberg is by far the biggest spender with over $300 million in ads placed and plans to dramatically increase advertising  in the weeks ahead.  During Canada's last federal election much advertising was spent on digital  followed by TV and little in radio and newspapers. So far in the US candidates are spending the most on TV and radio followed by digital and social media platforms.

Total ad spending for the 2020 US election is predicted to exceed $3.5 billion which is 11% more than the 2016 election.
https://www.cnbc.com/2020/02/10/bloomberg-ad-spending-spree-is-a-bonanza-for-local-broadcasters.html