When it comes to possible outcomes on Tuesday night, I see three potential scenarios.

1. The Classic “Tsunami” Election

We can put the 1994/2006/2010 midterms into this category. In this scenario, the bottom drops out for the party in the White House. Not only do the closest races tip to Republicans, but the GOP picks up seats in unexpected places. 

Two things need to happen for this scenario to play out: 1) Democratic voters are less motivated to vote while Republicans turnout at much higher levels and 2) independent voters break decisively toward Republicans by 12-15 points. 

In this scenario, Republicans would win at least 30 House seats and 3-4 Senate seats. 

How Do We Know If This Will Happen: 

Watch the New Hampshire Senate race. Polls close in the Granite State at 7 pm. Republicans have argued for months that Democratic Sen. Maggie Hassan is vulnerable. However, they failed to put up a top tier candidate, allowing her to control this contest's narrative for months. If she loses, we should expect to see Republicans picking up at least two, if not three Senate seats. 

In the House, watch VA-10, where First Lady Jill Biden is rallying voters on election eve. This northern Virginia seat voted for Biden by 18 points. If Republican Hung Cao defeats Rep. Jennifer Wexton (D), it’s a sure sign that the blue firewall has been breached. 

2. A “Wavey” Election

The closest historical example would be the 2018 midterms. In this scenario, turnout is roughly even to slightly better for Republicans. Independent voters, however, break decisively for Republicans (say by 10-12 points). The closest races break for Republicans, but there are fewer ‘surprise’ pick-ups. 

This scenario would produce a GOP gain in the House in the 20s and a likely one-seat gain in the Senate. 

How Do We Know If This Will Happen:

Watch the Pennsylvania Senate and IN-01 races. A Dr. Oz win in Pennsylvania would not just give GOPers a morale boost but would serve as a serious roadblock for continued Democratic control of the Senate. 

To get into the 20+ seat range, Republicans need to pick off districts that voted for Biden by 6 points or more in 2020. Heavily blue-collar IN-01 voted for Biden by 8 points. 

3. A Red Ripple 

We don’t have an analog in recent years for this type of midterm election. In this scenario, Democratic and Republican turnout is basically equal — with both sides able to juice their base. Instead of breaking decisively for Republicans, independent voters give Republicans a small advantage. Republicans pick up seats in pink/red districts and states, but fail to make gains into districts or states that Biden won handily in 2020. 

In this scenario, Democrats lose the House by a very small margin (maybe 8-12 seats) and Democrats keep the Senate. 

How Do We Know If This Will Happen:

Watch the Pennsylvania Senate and OH-13 races. If Democrats win the Pennsylvania Senate, this does not guarantee they will hold the Senate. But, it means they can afford to lose one of their own incumbents and still hold onto a 50-50 senate. 

If Republicans are going to have a good night, they have to be able to win CDs like the open Akron-based 13th CD in Ohio. If Republicans aren’t winning in districts that Biden narrowly carried (he won here by 3 points in 2020), it’s hard to see how they win in much bluer territory. 

So which is the more likely outcome on Tuesday?

For me, it’s scenario number two: the "wavey." 

For one, we are looking at yet another high-turnout election. Democrats may not be able to equal GOP enthusiasm, but they aren’t going to sit this one out. Nevada’s non-partisan guru Jon Ralston argues “The early voting numbers don’t indicate a red wave, just the possibility of one if everything breaks right for Republicans. This is not like 2014, when all the early voting data confirmed a red wave — I knew after a couple of days — and it was just a question of how many boats would be lifted by the red tide. This year, the Democrats have a slight advantage with more mail to come enhancing that.” 

The most recent NBC poll found Democratic enthusiasm/interest to vote basically tied with Republican interest; the first time in NBC midterm polling that the in-party is not getting swamped on this indicator. For example, back in the ‘tsunami’ years of 2006 and 2010, the ‘out party’ had anywhere from a 13 to 17-point advantage on interest in the election. 

However, other national non-partisan polls — Marist, Washington Post/ABC, and CNN — do show an enthusiasm advantage for the GOP. 

The question of how big a wave may be coming ashore will be what kind of turnout we see on Election Day. For the last five years, this is where we’ve seen the GOP surge. But, Democrats are hoping that their 2018/2020 voters, many of whom voted by mail during the pandemic, will show up in force at the polls this time around. 

Then there’s the generic ballot. Right now, Republicans have a lead of anywhere from 1.1 to 2.5 points. That’s enough to flip the House. But, if these numbers turn out to be accurate - Republicans win the national house vote 50-48 or 51-47 — that would represent a 4-6 point swing to the GOP from 2020; the smallest shift in the national House vote between a presidential and midterm year in 16 years. For example, in 2004, Republicans won the national House vote by almost 3 points. Two years later, Republicans won the national House vote by 6.4 points, a nine-point shift to the Democrats. The most dramatic swing came in 2010 (a more than 17-point swing to Republicans from 2008). 

Ultimately, however, I’m a big believer in the fundamentals. And right now, the mood of the electorate is dour. The president is unpopular. And inflation remains a persistent and unrelenting pressure point in the lives of average Americans. Those fundamentals alone give Republicans an outsized advantage. Keeping the bottom from dropping out on Democrats, however, are some structural fundamentals of their own: an optimal Senate map with weak/flawed GOP opponents in those key races; a House map that is also pretty well-sorted; a polarized electorate that rarely defects from its partisan leanings; and a Democratic base that is more engaged than we’d expect to see in a ‘tsunami’ year. 

More from the Cook Political Report

CPR 2024 National Polling Average
Cook Politcal Logo