This is a big electoral week in the UK, with voting of some kind taking everywhere, except in Northern Ireland.

Of course, the big one is the Scottish Parliamentary election, in which the Scottish National Party is seeking an electoral mandate to demand another referendum on Scottish independence.

And there is an election to the Welsh Senedd, in which constitutional issues are much higher up the agenda than in any previous vote.

Then there is the London Assembly election, 13 directly elected Mayors (including London), 39 police and crime commissioners, and around 5,000 councillors in 143 English councils.

Oh, and there is a parliamentary by-election for the Westminster constituency of Hartlepool, which has been a Labour seat since 1964, but which is now a closely fought battle, with the Conservatives eyeing an unlikely gain.

And that is due to Brexit.In the 2016 referendum, the constituency voted 69.6% to leave the EU.In the 2019 General election Labour got 37.7% of the vote, followed by the Conservatives on 28.9% and the new element in the mix – the Brexit Party, which got 25%.

And where that 25% goes this time will likely decide the seat.Labour is standing a candidate who had previously argued in favour of staying in the EU, while the Brexit party has changed its name to Reform, and may not get much recognition.

The Conservatives can push home their credentials as the party that delivered Brexit and are going all out to win.The parliamentary arithmetic won't change much, but it would not look good for new-ish Labour leader Kier Starmer, were he to lose in one of the so called "Red Wall" seats. In Hartlepool, Prime Minister Boris Johnson may well be a vote getter – a politician who delivered what he promised, never mind the Westminster sleaze allegations that have erupted in recent weeks.

Boris Johnson delivered Brexit which was key pledge

This is one to watch to see which way the wind is blowing in England. But only in England. Other parts of the UK are different – indeed this electoral round may show just how politically disunited the United Kingdom is becoming – with England becoming more dominated by the Conservative Party, which is adroitly playing to an increasingly nationalistic audience in England.

While the Scottish National Party does the same in Scotland. Meanwhile, Wales may be the last redoubt of the Labour party – thanks to a first minister who has skillfully kept nationalist inclined voters with the party by talking about alternatives to independence, such as Federalism within the UK.

In contrast, the Labour Party in Scotland is likely to finish in third place in the battle for Holyrood once again. Squeezed between the stark nationalism of the SNP and the stark Unionism of the Conservative Party, Labour lacks a clear simple message to sell the voters, some of whom are simply jaded from Labour's previous dominance of Scottish politics.

North of Hadrian's Wall, Mr Johnson is definitely an electoral liability. He won't be campaigning here, unlike other parts of the UK. But Mr Johnson was disliked well before his current problems, and the issue of how much his Downing Street flat cost to redecorate is gaining little traction.

For this election is, once again, all about the national question. The SNP will win, in the sense of being the largest party after Thursday's vote. They will form the next government, be it a continuation of the minority government that Nicola Sturgeon has led for the past five years with the support of the Green Party, or a formal coalition with the Greens.

Labour Party leader Kier Starmer

The latter expect to pick up some extra seats, buoyed by the rising Green tide across Europe – and by the Scottish Greens commitment to the cause of Independence. For younger voters in particular, they are becoming a nationalist alternative to the SNP.

But the SNP want more – they want an overall majority, in order to press home their claim to the right to hold a second referendum on Independence. Taking in Westminster, European Parliament, Councils and Scottish Parliament polls, this will be the fifth election in a row in which the SNP has emerged as the biggest party since the Independence referendum of 2014.

The 129 seats in the Scottish parliament are filled by two systems, so everybody who votes casts two ballot papers.

This they say gives them a moral right to seek the power to hold a legal referendum some time during the term of the next parliament.

They face two difficulties with this approach. Firstly, the ultimate power to permit a legal referendum resides with the UK government in Westminster, led by Boris Johnson – who does not want another referendum.

Secondly, they are trying to win an overall majority in a form of proportional representation electoral system that is designed to make it really hard for any party to get an overall majority, one in which coalitions are the norm.

The 129 seats in the Scottish parliament are filled by two systems, so everybody who votes casts two ballot papers. The first is for one of 73 Constituencies, in which a single member is elected by the first past the post method. The SNP will win most of these seats.

For the SNP to get an overall majority, they need to improve on their 2016 performance by six seats.

The remaining 56 seats are filled from eight regional List votes (7 MSP in each).Crudely put, the better a party does in the Constituency seats, the worse it does in the List seats – which helps the smaller parties like the Greens – and nowadays Labour. A new party called Alba, led by the former leader of the SNP Alex Salmond, is also trying to get in via the List system (it's not contesting any of the Constituency seats).Alba is polling poorly, but it may manage to get two or three seats.

They would add to the pro-independence majority in the Parliament – but could prove to be awkward for SNP leader Nicola Sturgeon – especially if Alex Salmond gets a seat (he is standing in the North East Region, Stretching from Dundee to Aberdeen).

For the SNP to get an overall majority, they need to improve on their 2016 performance by six seats. Most polls have them coming up short by between two and five seats. But the movement is within the margin of error for polls, and with the party putting in a special effort to boost its share of the list vote in this final week, it's too close to call.

They are also targeting several marginal or vulnerable seats – notably Edinburgh Centre, where Ruth Davidson of the Conservatives won last time, but is not standing in this election – despite being the Tory's best performer in debates against Nicola Sturgeon (She is going to the House of Lords, in semi-retirement from politics.She is not a fan of Boris Johnson, so perhaps she is biding her time for a return in the future).

Another target is Dumbarton, where the Labour incumbent Jackie Bailie held on last time by just 106 votes. She has held the seat since the first Parliament election in 1999, and is a well-known figure in Scottish politics (most recently being seen in the parliamentary committee inquiring into the state's actions against Alex Salmond when allegations of sexual misconduct were made against him).

When we visited the constituency last week nobody raised the Salmond/Sturgeon power struggle as an issue – the local hospital was the local issue, the Independence referendum was the national issue.

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The SNP did achieve an overall majority once before in 2011 – and it was that breakthrough that led David Cameron to grant the referendum request – so there is a precedent to be followed, something that is important in the Westminster system of government.

So there is no mystery about this – a vote for the SNP is a vote in favour of holding another referendum.

Which is why the counterattack on the SNP is mostly about referendum issues – EU membership, the fiscal rules of the EU, the single market and the hard border needed with England (destination for 60% of Scottish exports), what currency would be used by an Independent Scotland, a return to the Common Fisheries Policy.

Many of the arguments made are the mirror image of those deployed by those who wanted Brexit, and most of the people making them are Brexiters.

They also have a new argument – Covid vaccines. If Scotland was in the EU, they say, the SNP government would have been lumbered with the EU's less than rapid vaccine rollout.

Critics also say that Scotland's Covid death rate has only been slightly lower than England's.

Scottish First Minister Nicola Sturgeon

Nevertheless, the First Minister, Nicola Sturgeon, is rated highly by the people who will vote in Thursday's elections: recent polling for the BBC found 74% of Scots thought Nicola Sturgeon had done a good job in dealing with the pandemic: in contract just 19% thought Boris Johnson had done a good job.

It's a similar picture for the different administrations, with 72% saying the Scottish Government had done a good job, but just 25% saying the UK government had done a good job. In part this may be explained by the daily covid news conferences in Scotland, most of which have been presented by the First Minister.

She is an extremely effective and able communicator, and clearly benefits from being seen to be in charge of the government response on a daily basis. Academics also point to her willingness to quickly apologize when things go wrong.

Nevertheless, Ms Sturgeon – like all political leaders everywhere – is being judged on her perceived handling of the Covid pandemic – and the perception is good for Nicola Sturgeon.

The financial and economic arguments in favour of the Union, put forward in 2014, are if anything even more effective now

So once again the key attack issue is the Independence referendum with many critics claiming the SNP has not spelt out a clear and credible plan for demerging from the UK, for joining the EU, for the border with England or the currency it will use, or the fiscal transfers it gets from the UK. Ms Sturgeon's counter argument is – this is an election, not a referendum: when there is a referendum, then the SNP will present its plans.

As Nicola Sturgeon put it in an interview on BBC Scotland's Sunday Show at the weekend: "commentators and opposition politicians can't have it both ways, they can't say I should have spent the last year focusing on Covid which I've done, and then say you should have spent the last year, you know, developing the plans for independence. Thursday is not an independence referendum; it's not asking people to say yes or no.

"When we ask people to make that choice, just as we did in 2014, we will put forward a detailed perspective.... let's not allow project fear mark two - even before there's a referendum campaign - to start dominating the agenda."

And yet project fear is playing a part in this election – aided and abetted by Covid. The financial and economic arguments in favour of the Union, put forward in 2014, are if anything even more effective now in chipping away support from the nationalists. Because the biggest fear right now is of the economic hit that Covid has caused. On top of the economic hit caused by Brexit.

It makes the argument that Independence could be even more damaging to the economy much more real, and it seems may be making more people hesitant to go all out for independence – at least at this time.

Watch Sean Whelan's report on Scotland on the eve of this crucial election on Prime Time on RTÉ One Tuesday, 4 May at 9.30pm