Britain has not faced a more critical election in decades than the one it faces on Thursday. The country’s future direction, its place in the world and even its territorial integrity are all at stake, primarily because this is a decisive election for Brexit. The choice is stark. The next prime minister is going to be either Boris Johnson, who is focused on “getting Brexit done” whatever the consequences, or Jeremy Corbyn, who with a Labour-led government will try to remodel society with a programme of nationalisation and public spending.

Both main parties are offering heretical gambles against the tenets of mainstream thinking. Both are asking voters to join their revolts. Both have also become less pluralistic and more sectarian. Many traditional Conservative and Labour voters have been estranged from their parties. A sourly introspective and inward-looking campaign mood is further curdled by political misinformation. There is still a deep longing for community, but how to give meaning to it without giving way to exclusion or xenophobia remains unresolved. A Tory decade of self-defeating austerity has produced average wages lower than in 2008. Tent cities and food banks have become ubiquitous. Despite the existential threat of the climate emergency, the UK is not on track to meet our carbon dioxide reduction targets.

A different electoral system and a more deliberative politics, allowing society’s losers as well as winners to buy into political decisions, might have helped. The Guardian has urged such an approach as part of a solution to Brexit. Instead, a struggle for power within both the main parties has shaped an election in which many wish they faced better choices. Britain needs modern parties to correspond to the range of people’s lives and concerns. In their absence, voters in Wales, Scotland and Northern Ireland, as well as large parts of England, feel cut off from Westminster debate.

An outrageous prime minister

The Guardian’s long-held beliefs of internationalism, sustainability, social justice, constitutional reform and liberal acceptance are the standards by which this newspaper measures today’s adversarial politics and the imperfect set of choices that faces voters. The country is hurting. People are scared – for the planet, for their children’s future, for civic peace. In this era of Donald Trump, Britain’s parties have sought to channel voters’ indignation rather than hear their grievances. Mr Johnson uses conservative social positions to draw poor voters into betraying their own economic interests. Mr Corbyn plans to put on the citizen’s side a state so large it seems impractical. The Liberal Democrats’ moderate message, with its admirable position on electoral reform, is compromised by the fantasy of revoking Brexit.

In his brief time in office Mr Johnson has behaved outrageously. He has lied to the Queen, lied about Brexit and runs scared of serious interrogation. He is a divisive figure with a record of deliberately offensive comments. He bullies institutions such as the BBC and the judiciary for daring to hold him to account. His party’s manifesto dog-whistles with slogans hinting at a hardline approach to immigration. Hate and division have flourished under him. The claim that he can bring Britain together is risible. Mr Johnson promises no end to austerity; spending outside of health will be 14% lower in 2023 than in 2010. A promised tax cut for workers amounts to a saving of 23p a day – as services crumble. On climate his proposals are shamefully inadequate.

If the Conservatives win a majority, Britain will leave the European Union on 31 January 2020. In Tory eyes this would honour the referendum result of 2016. Any form of Brexit would be a tragedy for this country, but Mr Johnson’s would be disastrous. He aims to strike a future trade deal with the EU by the end of 2020; this is only possible if he agrees to the EU’s terms. Yet a significant part of the Tory party craves a small-state, deregulated Britain to compete with the EU. The more regulatory divergence the government wants, the harder it will be to negotiate an ambitious deal and the longer it will take to do so. If Britain follows Mr Johnson, it will leave without a deal, which would be considerably worse for the economy than a Corbyn-led government.

Mr Corbyn has had a low-key and troubled campaign. His best moment was his exposure of the danger to the NHS from Mr Johnson’s US trade deal plans. Labour has good ideas. But it may have overwhelmed voters with its gigantic offer. Labour’s manifesto seeks to remove the market from as many aspects of life as possible and wants to curtail the power of the mega-rich. It plans to build 100,000 council homes a year. It is offering free national social care, abolition of tuition fees, and pension payments for women who have been treated unfairly. Labour’s green policies are substantial and meaningful.

Not perfect but progressive

Labour seeks to undo the damage begun by Margaret Thatcher 40 years ago and to replace it with a more social democratic Britain. The country would be the better for that. But Mr Corbyn’s factionalism, his lack of a campaign narrative and his repeated overpromising has seen him struggle to persuade enough voters his plan is achievable. Mr Corbyn’s own unpopularity could also scupper Labour in this election. His obdurate handling of the antisemitism crisis has disrupted the message of hope. Anything less than zero tolerance against racism tarnishes Labour’s credentials as an anti-racist organisation. The pain and hurt within the Jewish community, and the damage to Labour, are undeniable and shaming. Yet Labour remains indispensable to progressive politics.

There is an understandable temptation, given the flawed choices on offer, to treat Thursday’s moment of decision with something close to despair. But there is a necessary and vital job to be done. This election is critical because the country is in the last-chance saloon on Brexit. If the Conservatives win, there will be no return. Brexit will sunder our links with Europe and pitch us into the arms of a reactionary US government. It threatens the breakup of Britain and to destroy the fragile peace in Ireland.

Making a difference

It is not enough to tackle Brexit. The next prime minister must tackle the causes of Brexit too – reaching out to the left-behind with plans for jobs and public services which show that the government will make a difference to their lives. Despite our misgivings, we believe that a vote for the Labour party offers the best hope for the country. A Labour-led government seems only possible with the support of parties that back its policy on a second referendum on Europe. It is likely also to have to meet the demand for a second independence poll in Scotland. That means backing candidates who can defeat the Tories in constituencies where Labour is an also-ran – from the SNP, the Lib Dems, the Greens and Plaid Cymru to pro-European independents. Think of the electrifying impact of relieving Mr Johnson of high office and stopping the pro-Brexit Tory party in its tracks. Thursday is a fleeting opportunity to stop an unwanted national calamity – and address the reasons behind it. Voters must seize the day.