JUS News looks at 16 constituencies in the region and assesses the likely outcomes at the general election on 8 June.
Labour won 15 of them two years ago, with a combined 50% of the vote in South Yorkshire.
All predictions come with warnings. Opinion polls can be misleading, as they were in 2015. Even if they are accurate, the swing may be different in South Yorkshire to the rest of the country. The effects of the EU referendum results are hard to assess, especially in traditional Labour strongholds which voted heavily for Leave. And much will depend on the strength of the local candidates, many of whom are yet to be selected.
2015 result: Labour 56%, Ukip 22%
Held by Dan Jarvis, a former Army officer, Barnsley Central is almost certainly out of reach for both the Conservatives and Ukip, despite a strong Leave vote in last year’s EU referendum. Many moderate Labour MPs would like the telegenic Mr Jarvis to run for the leadership, although he declined to do so in either 2015 or 2016.
2015 result: Labour 55%, Ukip 24%
Like Barnsley Central, this seat and its predecessors have elected Labour MPs since 1935. Ukip would need a 16% swing to change that, which is unlikely, and the Conservatives were some 40 points behind in 2015. Incumbent MP Michael Dugher, a strong critic of leader Jeremy Corbyn, is standing down, with union officer Steph Peacock chosen as the new Labour candidate last week.
2015 result: Labour 48%, Conservative 18%
A seat once held by Tony Benn is likely to elect a Labour MP again, although if the Conservatives match their national polls they may return their best performance there since the 1980s. The Liberal Democrats, who fell to fourth in 2015, may recover some ground in a seat which they held from 2001 until current Labour MP Toby Perkins took it from them in 2010.
Derbyshire North East
2015 result: Labour 41%, Conservative 37%
The Conservatives only need a 2% swing to unseat Labour MP Natascha Engel. Derbyshire North East is the 17th-most vulnerable Labour seat in the country and more marginal than any in South Yorkshire. If the national polls are anything like accurate in the region, the Tories will hold the seat for the first time since 1931.
2015 result: Labour 49%, Ukip 24%
The seat ought to be safe for Labour, although they have fallen below 50% of the vote in the last two general elections as Ukip have gained significant ground. Rosie Winterton, who was Labour’s chief whip in the Commons until she was sacked by Mr Corbyn last year, is running for re-election.
2015 result: Labour 52%, Ukip 23%
According to the best available estimates, Ed Miliband’s constituency had the highest Leave vote in South Yorkshire at last year’s referendum, and the sixth-highest in the country. However, the Conservatives and Ukip finished less than 2,000 votes apart in 2015, and as long as they take pro-Brexit votes from each other, Mr Miliband with his high profile ought to be safe.
2015 result: Labour 46%, Conservative 25%
Labour have held the Don Valley constituency since 1922, but it could yet be competitive in a particularly large Conservative landslide. The Tories came second there in 2015, earning their second-best result in South Yorkshire, and would need an 11% swing to unseat the Labour MP Caroline Flint, a critic of Mr Corbyn who was first elected in the New Labour landslide of 1997.
Penistone and Stocksbridge
2015 result: Labour 42%, Conservative 28%
The most likely South Yorkshire seat to change hands in 2017. Labour’s Angela Smith, an MP since 2005, held the seat two years ago, but the Conservatives recorded their highest share of the vote in the county there. The Tories’ required swing of 7.2% is around the figure they have been reaching in national opinion polls; the result may well be very close.
2015 result: Labour 53%, Ukip 30%
A very pro-Brexit seat, where more than 70% voted Leave in 2016, Ukip had their strongest performance in South Yorkshire in 2015 and where even the BNP had their third-best result in 2010. Nonetheless, Labour were far enough ahead in 2015 that Sarah Champion, who has worked hard to move on from disgraced former MP Denis MacShane, should survive.
2015 result: Labour 44%, Ukip 28%
Labour have won Rother Valley at every general election since the seat was created in 1918, by a majority of more than 10% every single time. The incumbent, Kevin Barron, has held the seat since 1983. Nonetheless, the 10% swing necessary for the Conservatives to flip the seat is not completely out of the question, if they could attract enough voters who supported Ukip in 2015.
Sheffield Brightside and Hillsborough
2015 result: Labour 57%, Ukip 22%
One of the safest Labour seats in the region, formerly held by David Blunkett and won comfortably both by Harry Harpham at the 2015 general election and by his widow Gill Furniss at the 2016 by-election prompted by Mr Harpham’s death. The Conservatives came a poor fourth at the by-election, while Ukip’s share of the vote fell. Ms Furniss should be fine.
2015 result: Labour 55%, Green 16%
A second-place finish for the Green party in 2015 prompted former leader Natalie Bennett to sell her house in London and challenge incumbent MP Paul Blomfield in Sheffield Central. However, with the Conservatives improving and Liberal Democrats likely to gain in a very pro-Remain constituency, Ms Bennett will be in a three-way race for second. Such divided opposition should secure Mr Blomfield’s re-election.
2015 result: Liberal Democrat 40%, Labour 36%
The Liberal Democrats’ then-leader Nick Clegg held off a fierce Labour challenge to hold his seat with a 4% majority in 2015, the closest result in South Yorkshire itself. With his party energised by opposition to a hard Brexit, Mr Clegg should have an easier time in 2017 against Mr Corbyn’s struggling party, in a seat which voted commandingly for Remain in the referendum.
2015 result: Labour 48%, Ukip 17%
Louise Haigh, the youngest Labour MP at 29, should be safe enough in a seat which last elected a Conservative MP in Edward Heath’s triumph of 1970. Ukip came second in 2015, although their share of the vote was unimpressive for the region, and while the seat voted to Leave it did so by less than most of South Yorkshire, according to estimates.
Sheffield South East
2015 result: Labour 51%, Ukip 22%
Current MP Clive Betts, who has been somewhat critical of Mr Corbyn’s leadership, won the seat comfortably in 2015, increasing his majority from the 2010 election. The Conservatives may supplant Ukip in second, but only in the most extreme landslide for Theresa May’s party would they threaten a seat which Labour has held in some form since 1935.
Wentworth and Dearne
2015 result: Labour 57%, Ukip 25%
The Leave campaign won 65% or more of the vote in every ward in Wentworth and Dearne at last year’s referendum. Still, Ukip were a long way behind in 2015, and the Conservatives finished some 40 points behind Labour, making a change of hands unlikely. John Healey, a minister under Tony Blair and Gordon Brown, should hold the seat fairly comfortably.