In September, Democratic TV advertising impressions in nine swing states climbed eight percentage points to a 58% share of all political impressions, according to Vizio's Inscape data.

At the same time, Republican-backed TV dropped eight points to a 40% share. 

In three key swing states, Democrat political advertiser impressions are at a 64% share or more: Michigan (68%); Arizona (65%) and Wisconsin (64%). 

Democrat political advertising has also topped Republican efforts in terms of rising reach -- 36% to 29%.

In addition, Democrat-backed frequency of ad messages into a TV home per month is up to 45 messages in September (versus 35 in August). In contrast, Republican-backed ads are at 37 (versus 38% in August).

Inscape also says there is a 31% overlap in ad message exposure across Democrat, Republican, and Independent messages into the home -- a 129% increase since May of this year.

Looking specifically at the Presidential race, Vice President Kamala Harris has taken the top political advertising spot in seven of nine swing states -- 44% in Michigan, in terms of reach; 40% in Wisconsin, Pennsylvania, and Nevada; and 38% in Arizona; 36% in North Carolina and 35% in Georgia. 

Democrats are putting slightly more advertising messages on streaming platforms than Republicans (31% versus 26%) -- slightly lower than Republicans (69% versus 74%).

Inscape linear and streaming data comes from over 24 million opt-in devices.