The battle to win the Republican Iowa caucus is the most expensive on record, with over $120 million spent on ads by the campaigns and their affiliated political action committees in the Hawkeye State, according to data provided to CNBC by AdImpact. Around $84 million of the $120 million total ad buys came from campaigns and allies of the top three candidates, Trump, Haley and Florida. DeSantis' campaign and two outside allies have spent a combined $30 million on TV, digital, and radio ads in Iowa. One of the two DeSantis super PACs, Never Back Down, has knocked on over 915,000 doors in the Iowa, according to the organization. As for Trump's super PAC, MAGA Inc. would not provide data on what efforts they've made outside of their ad spending in support of the former president.

---

Persons: Donald Trump's, Trump's, Nikki Haley, Trump, Haley, Ron DeSantis, Michael Franz, DeSantis, Charles Koch, Bill Riggs, Riggs, they've, We'll, backslapping, Taylor Budowich Organizations: Republican, CNBC, AdImpact, GOP, Monday's, South Carolina Gov, Gov, Inc, Wesleyan Media, Prosperity, Iowa Caucus, Hawkeye State, AFP, Iowa, Trump's, MAGA Locations: Des Moines , Iowa, Republican Iowa, Hawkeye, Iowa, Florida, New Hampshire, South Carolina