House Democrats, as we have been reporting now for months, have the wind firmly at their back this year. All signs are pointing to a better than 50-50 shot at taking control of the House, perhaps by a decent margin. Even so, we’ve also noted that Republicans have a built-in structural advantage — namely few swing seats to defend. Moreover, the conventional wisdom has held that the map has gotten much less favorable to Democrats in the House since 2006, thanks in large part to the fact that Republicans controlled the redistricting process in many significant battleground states in 2012, taking many formerly competitive seats off the table.

But, as Senate Leader Mitch McConnell warned everyone very early in the cycle, “don’t fall in love with the map.” In fact, when you look more closely at the kinds of districts Republicans are defending in 2018, they don’t look much different from those they had to defend in 2006. For example, there are about as many competitive GOP-held seats in play today in districts with a slight GOP lean (PVI of R+1 to R+5) (23) as there were right before the election in 2006 (22). And, while it’s true that there are few “low hanging fruit” type of districts for Democrats to pick-off (just 23 districts held by Republicans voted for Hillary Clinton), there weren’t many easy lay-ups in 2006, either. Back in 2006, Republicans held just 18 seats won by Democrat John Kerry in the previous presidential election. By the election of 2006, just 15 GOP-held seats (or 27 percent of the total number of GOP-held competitive districts), were in districts that had a slight Democratic lean (a PVI of Even to D+8). Today, of the 40 most competitive seats held by Republicans, 10 (or 25 percent), have a slight Democratic lean (Even to D+5)

In other words, it’s not that map has gotten that much worse for Democrats since 2006; the battleground itself has shifted. For example, in 2006, Indiana, Ohio and upstate New York accounted for 25 percent of the most competitive GOP held seats. This year, California, New Jersey and Texas account for 30 percent of the most competitive GOP seats. We’ve swapped upstate New York with Orange County, California and central Indiana for central New Jersey.

You will also notice that the plurality of seats won by Democrats in 2006 (40 percent) came not from Democratic-leaning seats, but from districts that had a slight GOP advantage. Another 23 percent of the seats Democrats won that year came from districts that had a PVI of R+6 or greater. If Democrats won the same percentage of seats from each category this November as Democrats did in 2006, they would net 22 seats — or two seats shy of the 24 they need to win the House. The challenge for Democrats today is to expand the playing field. Of the 26 GOP-held seats in Likely Republican, two have a Democratic PVI, nine have a PVI between R+1 and R+5 and 15 have a PVI of R+6 or greater. Winning just two of those 26 would get Democrats to the magic number of 24 seats.

November 8, 2006 Cook Political Report Ratings of GOP-Held Seats

PVI Total Number of GOP Seats In Lean R/Lean D/Toss Up Total Open Seats per category Total Seats Won By Dems. Total % Won From PVI Category PVI Category as Percent of Total Seats Won Even to D+8 15 2 9 60% 37% R+1 to R+5 22 9 12 55% 40% R+6 or > 18 5 7 39% 23% Total 55 16 28

January 12, 2018 Cook Political Report Ratings of GOP-Held Seats

PVI Total Number of GOP-Held Seats in Lean R/Lean D/Toss Up Total open seats per category If Dems Hit Their 2006 Win % - Seats That Would Be Won By Dems EVEN to D+6 10 3 6 R+1 to R+5 23 5 13 R+6 or > 7 2 3 Total 40 10 22

One difference that works to Republicans benefit this year is the fact that Democrats have to defend more vulnerable House seats today than they did back in 2006. In 2006, the most vulnerable open seat Democrats had to defend was in OH-06 in southeastern Ohio which had a PVI of EVEN. This year, Democrats are defending three open seats in GOP-leaning territories: MN-01 (PVI R+5), NH-01 (PVI R+2), and NV-03 (R+2).

The other challenge for Democrats is that the battleground in 2018 is taking place in media markets that are much more expensive than the ones in which they were competing back in 2006. In 2006, Democrats were playing in lots of relatively cheap media markets like Evansville, IN, Zanesville, OH and Louisville, KY. This year, almost all of the GOP-held seats in Toss-Up are in very expensive (to prohibitively expensive) markets like Los Angeles, New York City, Washington, DC, and Miami. It’s hard for Democrats to expand the playing field when they and their allies are going to have to spend a boatload of money just to compete in the districts already in play.

A more significant change between now and 2006, however, is partisan antipathy. Our friends over at Pew Research have been asking voters for many years if they have a favorable or unfavorable view of the opposite party. Not surprisingly, over the last 23 years, a majority of Democrats haven’t been big fans of Republicans and Republicans haven’t liked Democrats. But the intensity of that dislike — especially among Republicans toward Democrats — has increased rather significantly since 2006. Back in 2006, 75 percent of Republicans had an “unfavorable” view of Democrats, with 47 percent saying they had a “mostly unfavorable” view of Democrats and 28 percent saying they had a “very” unfavorable view. Fast forward to 2017 and you see that the percent of Republicans who hold Democrats in low opinion has jumped 6 points to 81 percent. But, more importantly, the percent who said they had a “very” unfavorable view jumped 17 points to 45 percent. In other words, Republicans are more hostile to Democrats today than they were in 2006. Why does that matter? Well, as we’ve already seen, Republicans hope that focusing GOP voters on what they dislike — namely Nancy Pelosi and a liberal Democratic Congress — will help to motivate them in a way that Trump and the GOP Congress cannot.

The 2018 map is not easy for Democrats, but it’s not any more challenging than the one Democrats faced in 2006. Midterm elections are a referendum on the party in power, not the party out of power. However, the dislike for the Democratic party among GOP partisans is more intense today than it has ever been. The question is whether that antipathy to Democrats will be enough to match the anger and opposition to Trump among Democrats and Democratic-leaning voters.