Data: AdImpact; Note: "Campaigns" include spending by candidates or in coordination with party committees; "Outside groups" includes spending by non-candidate groups and party committees; Chart: Axios Visuals
Republicans outspent Democrats on political advertising in Iowa by nearly $20 million.
The number includes presidential and down-ballot races.
By the numbers: Republican campaign and outside groups spent about $51 million in Iowa as of Oct. 31.