This is turning out to be a fascinating midterm election, pitting the Democratic wave against the Republican seawall.

Historic midterm voting patterns combined with national, state, and district-level polling data and off-year election results are combining to make a strong case for a classic midterm wave—obviously not what Republicans want to see. But district boundaries and natural population patterns provide at least some degree of protection for House Republicans. Similarly, in the upper chamber, the states that have Senate seats up tilt the playing field decidedly toward Republicans. As Shakespeare might (but probably wouldn’t) say, “The wave or the wall—that is the question.”

There is no question that passage of the tax-cut bill in late December was a huge shot in the arm for Republicans. Through much of 2017, many GOP partisans and independents who lean Republican had grown despondent over the inability of their party to repeal Obamacare or move many other desired pieces of legislation. The hope among Republican officials and strategists is that the enthusiasm among GOP voters for the tax measure would be contagious, and help among the 7 in 10 voters who identify as independents or Democrats. But polling over the past two weeks suggests that the boost for President Trump and Republicans was relatively contained and short-lived.

Fresher polling shows Trump’s approval rating has ticked back down after a brief rise. Remember, it’s always best to keep an eye on the averages; resist the temptation to cherry-pick polls, focusing on the ones that tell you what you want to hear and ignoring those with bad news.

The latest RealClearPolitics average of major polls has Trump’s approval at 41.2 percent, with disapproval of 54.8 percent. FiveThirtyEight’s average is 39.4 percent approve, 55.2 percent disapprove (in mid-February, the site had approval up to 41.5 percent and disapproval down to 53.2 percent). Similarly, the generic-congressional-ballot test narrowed a bit over January but has widened back out some, with less of a Democratic lead than in early December but still in the danger zone for the GOP.

With the Hill more focused on the generic-ballot test, the three most recent live telephone surveys are the CNN/SSRS survey taken Feb. 20-23, giving Democrats a 16-point lead over Republicans; Marist College’s Feb. 20-21 poll putting the Democratic edge at 7 points; and Quinnipiac University’s Feb. 16-19 poll putting Democrats up by 15 points. Among the online pollsters, YouGov (Feb. 18-20) has the Democratic margin at 8 points while Harris Interactive (Feb. 16-19) has it at 5 points.

For polling aficionados, there is a very smart article by Charles Franklin, director of the Marquette University Law School poll and a longtime political scientist at the University of Wisconsin, that looks into why so many polls differ and why the mix of polling in the averages has changed since the first of the year, illustrating the differences between robo-polls, internet polling, and the more traditional live telephone-interview surveys.

A subplot for this election is public attitudes toward the economy—what Republicans are banking on to save their majorities. The University of Michigan’s influential national survey of consumer sentiment for the first half of February showed consumer confidence rising to its second-highest level since 2004. On Tuesday, the other widely watched indicator, the Conference Board’s consumer-confidence rating, will be released; it, too, has been showing a far more optimistic base of consumers than prior to Trump’s election. The National Federation of Independent Business’s survey of small-business owners shows their confidence levels in recent weeks at the highest point since early 2005, no doubt linked to passage of the tax bill.

That leaves open the question of how much attitudes toward the economy affect Trump’s approval ratings and, by extension, Republican fortunes. Will the economy make voters less likely to rock the boat by changing control of the House and/or Senate, or are visceral attitudes for or against the president so great that they outweigh all else?

Another variable is the long-term effect of the Parkland, Florida school shooting. Events always look bigger immediately after the fact than they do much later, and while there is no question that Democrats and left-of-center voters are stirred up, they already were before the tragedy. Will this also fuel intensity on the other side? Will gun-control opponents be able to match the enthusiasm that their ranks had in opposition to and fear of President Obama—a force that drove their ranks to turn out in big numbers in the 2010 and 2014 midterm elections? The fact that both sides of the gun debate are now extremely motivated adds yet another wild card to this fascinating election.

This story was originally published on nationaljournal.com on February 27, 2018