GOP's war for eyeballs

Republicans are starting to trounce Democrats in political spending across the Senate map, and that advantage is now showing up in one of the metrics campaigns care about most: impressions.

Why it matters: Money matters in a campaign's closing weeks, but what campaigns are ultimately buying is voters' attention — and the price varies, depending on who is buying and when they place their ads.

• Beginning in September, campaigns and super PACs start competing for the same finite supply of advertising inventory. But the campaigns are guaranteed lower rates.
• Republicans are generating substantially more impressions — an estimate of the number of times an ad is seen — but their advantage isn't nearly as large as the spending disparity would suggest.

The intrigue: North Carolina is the only key battleground where Republicans have been spending more for fewer impressions in the first weeks of September.

• Democrats generated 245 million impressions supporting former Gov. Roy Cooper, compared with 226 million for Republican Michael Whatley— even while being outspent by Republicans $10.6 million to $9 million.
• Whatley has been consistently trailing Cooper in the polls.
• It is forcing Republicans to weigh whether to begin pulling resources there. One key GOP super PAC took down $6.5 million worth of ads for October, as Semafor first reported.

By the numbers: From Sept. 1 through Sept. 17, Republican advertisers generated 502 million impressions in Texas, compared with 331 million for Democrats, according to data compiled by Kinetiq Political Insights.

• Republicans, relying heavily on super PACs to bolster Attorney General Ken Paxton, spent $37 million over that period.
• Democrats spent $9.5 million, with much of that coming directly from state Rep. James Talarico's campaign.

In Ohio: Republican ads generated 406 million impressions supporting Sen. Jon Husted, compared with 320 million for former Sen. Sherrod Brown.

• Outside GOP groups accounted for much of Husted's advertising, with Republicans spending roughly $22 million on his behalf. Democrats spent $14 million for Brown.
• Husted will get another boost. Fairshake, the crypto industry's main super PAC, has reserved $30 million in Ohio to oppose Brown.

Driving the news: Republicans opened up a massive spending advantage in September, outspending Democrats on air in nearly every competitive Senate race.

• Those gaps have widened as more GOP-aligned super PACs have entered the fray.

Zoom out: Candidates get lower rates from broadcasters, meaning they get more airtime for fewer hard dollars than outside groups and super PACs.

• Super PACs can raise unlimited sums, but often pay many times more than candidates for comparable broadcast inventory.

Zoom in: Democrats' strength in online fundraising has helped their candidates amass large hard-dollar war chests, while Republicans have countered with a significant advantage in super PAC and party money.

• This year, a Supreme Court ruling opened the door for party committees to combine their funds with campaigns and get the lower rates.
• The NRSC estimates that coordinated spending can make its advertising dollars stretch three to 10 times further than they did last cycle, Axios reported. It's committing $46.5 million to coordinated campaigns across eight states.

The bottom line: Republicans are relieved that the big-spending super PACs have arrived in force.

• But that relief is tempered by concern that the cash infusion has come after some voters' views of the races and candidates may have already hardened.