Are We Absolutely Certain That Doing Unpopular Things Will Make Republicans More Popular?
By 
There is at least some reason for doubt:
There are certainly signs that the partisan fight over Brett M. Kavanaugh’s nomination to the Supreme Court goosed Republican enthusiasm for the midterm elections.
“This has actually produced an incredible surge of interest among these Republican voters going into the fall election,” Senate Majority Leader Mitch McConnell (R-Ky.) said to USA Today after the final vote to confirm Kavanaugh. “We’ve all been perplexed about how to get our people as interested as we know the other side is — well, this has done it.”
A survey by NPR, PBS NewsHour and Marist released last week indicated that McConnell’s excitement might be warranted: After trailing Democrats in enthusiasm during the summer, Republican enthusiasm for voting has caught up.
But that is only half the picture. More important is how those energized voters plan to cast their ballots — and a new CNN-SSRS poll suggests that the most enthusiastic voters are not those Americans most interested in rising to Kavanaugh’s defense.
Consider, for example, the responses to questions about how President Trump’s doing in his job or whether Kavanaugh should have been confirmed. Disapproval of Trump is higher among those who are more enthusiastic to vote, as is opposition to Kavanaugh’s confirmatio
Even starker is the difference in opinions of Kavanaugh personally. Those most enthusiastic about voting are much more negative on Kavanaugh than those not very enthusiastic about voting next month.
This is not what McConnell might expect to see. Given that negative opinions of Kavanaugh are even more negative than the population overall — albeit often slightly — it reinforces that the most enthusiastic voters, according to this poll, are more densely anti-Kavanaugh.
We see similar divides on a battery of questions asking Americans how they feel about Kavanaugh. Consistently, the most enthusiastic voters hold more-negative views of the court’s newest associate justice.
Increased Republican enthusiasm makes it very plausible that Kavanaugh failing without enough time to confirm a replacement before the midterms would have been, in the short term, the worst case scenario for Republicans. But it doesn’t follow logically from this that confirming Kavanaugh will be a net positive for Republicans. Maybe it will, but analysis that fails to take the backlash to the nomination into account is not very useful.
And Nate has a useful reminder:
One reason not to really trust the conventional wisdom about how Kavanaugh's confirmation will out play politically is because the conventional wisdom is overwhelmingly formulated by dudes. https://t.co/cUqI6Cw0nx
— Nate Silver (@NateSilver538) October 9, 2018
And, needless to say, the conventional wisdom on October 10 2016 was that Clinton was such a mortal lock she should be covered as if she was the president-elect.