US Midterm Elections: Key races and markets to watch in the battle for Congress

• US Midterms will be tremendous betting event
• Five Senate races still competitive
• House districts to form a Red Win or Red Wave
• In-running betting advice

Five days out, the signals from Betfair markets are getting clearer. The Republicans are near-certain to regain the House of Representatives, trading at odds of 1.091/11. Using our Democrat Seats market as a guide, where 199 or fewer is rated a 50% chance, they are forecast to lose 235-200.

The Senate is much closer, with the Republicans 68% likely to win a majority (defined as 51 seats, discounting Independent members, including those who caucus with either main party).

That rating has risen consistently in recent weeks, but the margin is certainly close enough to turn back towards the Democrats. The likeliest tally, based on our Republican Seats market, is 51-49 - an 18% chance at odds of 5.59/2.

Liquidity will spike in-running

So how best to trade what will be a tremendous betting event, with liquidity sure to spike as we near polling day and, as always, live in-running whilst the votes are being counted and declared?

If you haven't bet live on a US Election before, watching the vote scoreboard changing and driving the markets, I strongly recommend it.

A good plan at this stage is to build a position from which to enter the in-play period. For example, back a specific seat total or an overall target.

For example, I agree with the market assessment that 51 Republican Seats is favourite and have taken the 5.59/2 odds. My hope is that, during the night and following morning, those odds will trade much shorter. In the House market, I've backed 200-209 Democrat Seats at 4.03/1 with the same idea in mind.

For politics punters, these mid-terms are perfect training for the marathon 2024 US Presidential election. They are a great way to get to know the states, and districts, which almost always determine US elections. As the results come in, knowing the details of the most critical or bellwether districts offers a key strategic advantage.

We know which will determine the Senate and House, and which represent the most optimistic targets for each party. The FiveThirtyEight site is a solid reference for those states and districts, so I shall quote their forecast percentage.

The five closest Senate races

I've previewed the 10 competitive Senate seats here. However unless the forecasts - betting or psephological - are badly wrong, we can probably restrict calculations to five. Arizona, Pennsylvania, Georgia, Nevada and New Hampshire. These forecasts are subject to change but at the time of writing, these are the projections.

ARIZONA - DEMOCRAT HOLD - 56% BETFAIR, 65% FIVETHIRTYEIGHT

GEORGIA - REPUBLICAN GAIN - 60% BETFAIR, 55% FIVETHIRTYEIGHT

PENNSYLVANIA - SPLIT DECISION - OZ 58% BETFAIR, FETTERMAN 55% FIVETHIRTYEIGHT

NEVADA - REPUBLICAN GAIN - 75% BETFAIR, 58% FIVETHIRTYEIGHT

NEW HAMPSHIRE - DEMOCRAT HOLD - 64% BETFAIR, 72% FIVETHIRTYEIGHT

That equates to 52 or 51 Republican seats, depending on Pennsylvania, for which betting and forecasts are split.

As for the House, according to the current FiveThirtyEight forecasts for each district, the Democrats would need to win at least six districts in which the Republicans are favourite. Among those 223, only these six are rated less than 65% likely.

ALASKA-AT LARGE, PENNSYLVANIA-07, CALIFORNIA-22, OREGON-05, IOWA-03, CALIFORNIA-27

Eighteen districts to complete a Red Wave

On the other side of the ledger, there are 12 seats where the Democrats are favourite but are rated below 65%.

VIRGINIA-02, TEXAS-34, NEVADA-01, TEXAS-15, NEW YORK-19, RHODE ISLAND-02, MICHIGAN-03, PENNSYLVANIA-17, PENNSYLVANIA-08, NEVADA-03, MAINE-02, ILLINOIS-17.

The closest House market is the Fewer than 200 seats line in Total Democrat Seats - priced at even money the pair. If they lose all the above districts, they would end up on exactly 200. So in order to land the 'unders', at least one more target must be gained from the Democrats. A further six are rated below 70%.

NEW HAMPSHIRE-01, CONNECTICUT-05, NEW YORK-17, CALIFORNIA-13, ILLINOIS-06, MARYLAND-06

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Senate Majority

Total Republican Senate Seats

Total Democrat Senate Seats

House of Representatives Majority

Total Democrat House Seats