SMP’s announcement comes one week after the conservative Senate Leadership Fund booked $67.1 million for all of these five states as well as Kentucky. As we’ve noted before, major outside groups like to reserve well ahead of time so they can lock in cheaper ad rates before high demand for TV time brings prices up. That’s especially true in a presidential year where both major party nominees and their allies will be spending massive amounts in many, if not all, of these states.

These early reservations also give us an early window into what SMP expects the major battlegrounds to be in the contest to control the Senate, but they don’t tell us everything. For instance, SMP head J.B. Poersch suggested to the Post that his group was holding off on purchasing ad time in Montana, where GOP Sen. Steve Daines faces a challenge from Democratic Gov. Steve Bullock, because the state is unlikely to attract much presidential spending. And as we’ve written before, major outside groups can also always reduce or completely cancel reservations if a race looks like it’s already won or is too far gone to be salvaged.

Both SMP and SLF made by far their largest reservations in North Carolina, which isn’t a surprise. Six years ago this seat hosted what was the most expensive Senate contest in American history at the time, and if Democrat Cal Cunningham unseats GOP incumbent Thom Tillis, that means there's a good chance Team Blue will have won enough seats elsewhere—likely in Arizona, Colorado, and Maine—to flip the Senate

What’s a bit more surprising is that each group has booked about $13 million in air time for Iowa, where Republican incumbent Joni Ernst appears to have a clear advantage. While the Hawkeye State has been competitive turf for generations, Ernst herself won by a surprisingly lopsided 52-44 margin in 2014, and Donald Trump did even better there two years later. Iowa did move back towards Democrats last cycle when Democrats unseated two GOP House members, but Republican Gov. Kim Reynolds still won a full term 50-48 in a bad year for her party.

Unfortunately, no one has released a single survey this year of the likely matchup between Ernst and her likely Democratic rival, businesswoman Theresa Greenfield. The last poll we saw was a December Public Policy Polling survey for Greenfield’s allies at End Citizens United that showed Ernst ahead by a modest 47-41 margin. Both SMP and SLF, though, almost certainly have more recent numbers, and they’re each acting like they expect this to be a competitive race.

By contrast, SMP and SLF’s smallest reservation, at a bit over $5 million each, was in Colorado. The state supported Hillary Clinton 48-43, and several polls taken last year showed GOP Sen. Cory Gardner trailing former Democratic Gov. John Hickenlooper by double digits in a likely matchup. (We haven’t seen any new numbers since October.) However, while neither group has booked a huge amount of air time, neither is acting like the well-funded incumbent is doomed.

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