The Senate is slipping away from the Democrats

While races for control of the White House and the House of Representatives remain on a knife edge, the question of which party will win a majority in the upper chamber of Congress appears clearer.

Capitol Hill, Washington DC (via Shutterstock)

While the knife-edge race between Vice-President Kamala Harris and former President Donald Trump to become the 47th President of the United States is dominating the global news agenda, the congressional races for the House of Representatives as well as the Senate are heating up too, with huge ramifications, regardless of who next sits in the Oval Office.

The Economist’s prediction modelling now has the presidential race tied with Trump and Harris each winning 50 out of every 100 election simulations they run, whilst the ABC’s 538 election forecast has Trump victorious in 52 times out of 100 simulations and Harris in 48 out of 100. In terms of the states needed to win the electoral college, the non-partisan Cook Political Report has designated all of the closest seven battleground states of Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin as toss ups which could go either way.

It's clear the race between Trump and Harris is unbelievably close. Yet the down-ballot House and Senate contests are equally nail-biting. While they don't attract the same level of coverage as the presidential contest, they are incredibly important given that the makeup of Congress will shape the legislative agenda of whichever presidential candidate prevails on 5 November. 

In the House, whose 435 members play a key role in the passage of federal legislation are up for election every two years, the GOP is currently seeking to defend its slim majority. 

The balance of power in the lower chamber at present is 220 Republicans, 212 Democrats and three vacancies, meaning that the Democrats will most likely need to pick up four net seats in November to win control. With the makeup of the House likely to be decided by a number of swing districts, particularly in New York and California, most election modelling predicts that the race for a majority in the chamber is just as tight as the presidential contest. 

538’s forecast predicts that Republicans will win control of the House 52 times out of 100 with Democrats victorious in 48 out of every 100 simulations. The Economist’s model is more favourable to Democrats, suggesting that Harris’s party will secure a majority in the House 56 times out of 100 with the GOP winning 44 of every 100 simulations.

In stark contrast to the nerve-racking tightness of the races for control of the White House and the House of Representatives, the question of which party will win a majority in the upper chamber of Congress - the Senate - appears to be much clearer, and not good news for Democrats.

The Senate is made up of 100 members, two from each state, who serve six-year staggered terms, meaning that around a third of its members are up for election every two years. This cycle, control of the Senate hangs in the balance.

Having a party majority in the Senate is a huge deal, with the upper chamber able to confirm federal officials including Supreme Court judges, shape federal legislation and (as occurred twice during Trump’s previous term) vote on whether the President should be convicted and removed from office if they are impeached by the House.

The Democrats, along with independents who caucus with the party, currently control 51 Senate seats whilst the Republicans control 49 however this slim one-seat majority looks to be under serious threat. Given that whoever is Vice-President casts the deciding vote in the Senate if the vote is tied at 50-50, Democrats can only afford to lose one seat if Harris is elected in November or none at all if Trump comes back into office.

The Senate seats up for election this year are extremely unfavourable for the Democrats who find themselves defending 24 of the 34 seats up this cycle whilst the GOP are only defending 10. This numbers game alone is not what may give Republicans control of the Senate, it is the states in which seats are up for election. Seats which are disadvantageous to the Democrats.

In the solidly Republican state of West Virginia, where Trump carried by nearly 40 points in 2020, the retirement of conservative Democratic Senator Joe Manchin has essentially guaranteed at least one Republican pick up. Running in the open seat, the state’s former Republican governor, Jim Justice, is currently leading the Democrat Glenn Elliott by over 30 points in the most recent polls, effectively already reducing the Democrats to 50 Senate seats.

Meaning, even if Harris were to win the White House, the Republicans would only have to win one more of the other 23 seats they are challenging, assuming that they successfully defend all their 10 seats. This is where things becomes very difficult for Democrats who are defending Senate seats in Montana (a state which Trump won by over 16 points in 2020) and Ohio (a state Trump won by 8 points in 2020) as well as seats in the swing states of Arizona, Michigan, Nevada, Pennsylvania and Wisconsin.

By contrast, the only somewhat marginal seats that the Republicans are defending this cycle are in Texas (a state Trump won by five and a half points in 2020) and Nebraska (which, despite splitting its electoral college vote by congressional districts, tends to be a reliable Republican state).

In these crucial states, the current polling averages, according to ABC’s 538 analysis, show that the Democrats risk losing their Montana seat to Republicans whilst Joe Biden’s party are currently ahead in the seats they are defending in Arizona, Michigan, Nevada, Pennsylvania, and Wisconsin as well as Ohio where the Democratic incumbent is up by an average of just 1.6 points.

In the most threatened GOP seats, Ted Cruz remains around 3.5 points ahead of Democratic challenger Colin Allred while Deb Fischer in Nebraska is hanging onto a single point lead against independent challenger Dan Osborn, a former labour union leader.

While polling is never entirely reliable, with there being a significant polling error in both the 2016 and 2020 presidential elections, 538’s figures suggests the Democrats will end up with 49 Senate seats with 51 for the GOP if Fischer holds on in Nebraska.

Even if Fischer loses and Osborn decides to caucus with the Democrats, if Trump returns to the White House, JD Vance will have the tie breaking vote in the Senate, giving the Republicans control.

So it’s no surprise that 538’s modelling has Republicans winning control of the Senate 89 out every 100 election simulations they conduct and Democrats only maintaining their majority in 11 times out of 100.  The Economist’s model takes a slightly more favourable view of Democrats chances at 31 out of every 100 simulations but still views Republicans as strong favourites: winning 69 times out of 100.

With less than a week to go, races for the Presidency and the House are seemingly all to play for. Yet control of the Senate appears to be slowly but surely slipping away from the Democrats.