There are 119 Republican House members who should be VERY nervous today

Washington (CNN)It's easy -- and understandable -- to focus on whether or not Conor Lamb is going to wind up with more votes than Rick Saccone when all the ballots are counted from Tuesday's special election in Pennsylvania.

But the focus on the "W" sort of misses the point. And that point is this: This southwestern Pennsylvania district should have never been competitive -- or even close to competitive. This is not a swing district. It is not even a Republican-leaning district. It is, based on past presidential performance and congressional level results, a comfortably Republican seat.
And if comfortably Republican seats like Pennsylvania's 18th are competitive in this sort of national environment -- an unpopular president in the White House, Democratic base voters fired up over the prospect of sending Donald Trump a message -- then there are a whole lot of GOP members of Congress who need to start worrying this morning.
    One way to measure -- and I think the best way to measure -- just how titanic Lamb's apparent victory is (and what it means for the fight for the House going forward) is to look at how many other seats Republicans currently hold that have similar or less GOP-friendly profiles than Pennsylvania's 18th.
    Which brings me to the Cook Political Report's Partisan Voting Index or PVI. The goal of the PVI is to compare every congressional district to every other congressional district based on how it has performed in each of the last two presidential elections.
    So, in the case of PA-18, it has a PVI of R+11, meaning that in the last two presidential elections it has performed 11 points more Republican than the nation as a whole.
    That PVI score makes Pennsylvania's 18th district the 124th-most Republican district in the country. (The most Republican district in the country is Texas Rep. Mac Thornberry's 13th, with a PVI rating of R+33.)
    Here's where things get very, very scary for Republicans: According to the latest edition of the Cook PVI ratings, which are based on the 115th Congress, there are 119 seats currently held by Republicans that have PVI scores of R+11 or lower.
    One hundred nineteen! That's exactly half of the 238 seats Republicans currently hold -- HALF. It's far beyond the 23 seats that Hillary Clinton won in 2016 that are currently represented by a Republican. It's roughly five times as many seats as Democrats would need to pick up -- 23 assuming Lamb wins -- to retake the House majority come November. And it's well more than the 74 seats that the Cook Report ranks as marginally competitive as of today.
    Now, simply because a district looks similar to Pennsylvania's 18th based on presidential performance doesn't mean that each of these 119 seats will be in play this fall. This race had unique circumstances -- from the resignation of Rep. Tim Murphy (R) amid a sex scandal to the insider nomination processes that produced the skilled and telegenic Lamb and the far less skilled and telegenic Saccone.
    But for Republicans to dismiss Pennsylvania's 18th district as an anomaly is to miss the forest for the trees. No matter how bad a candidate Saccone was, he was a non-scandal plagued, GOP lawmaker running in a reliably Republican seat. He wins if the national political environment is neutral or even if it is tipped only moderately toward Democrats.
    That he appears to have lost should put every one of the 119 Republicans who sit in districts as bad or worse than PA-18 on high alert. It sure as hell looks like there is a wave building out in the country. And they need to batten down the hatches now in hopes of surviving it.