Not for the first time, Britons go to the polls with the European Union the unseen ballot question.

In 2013 David Cameron promised fractious Conservative members of parliament, chaffing under a coalition government, that a referendum on remaining within the European Union would be put before the people. Then it was the Brexit vote itself, with a majority of Britons voting for independence.

Now, with a general election tomorrow, the question revolves around who will steer negotiations: Theresa May’s Tories or Jeremy Corbyn’s Labor party?

For the Brexit purist, neither choice is satisfying. Mrs. May hadn’t campaigned for Brexit last year and, while she has said that “Brexit means Brexit,” the government’s opening gambit has been to accept minor concessions that belie the determination of Britain’s bid for sovereignty, whether, say, paying to participate in the single market and customs union or converting existing EU law to UK law.

As for Labor, while it has mouthed platitudes about respecting the Brexit referendum, its composition of loose variables — from those die-hard statist Europhiles to those who want a second referendum vote — leave much to be desired, as demonstrated by its approach to the EU: placate Europe for access to its markets, enshrine workers’ rights into law without corresponding care for the rights of entrepreneurial capital, and outright rejection of the Tory position that “no deal is better than a bad deal.”

The three terrorist attacks since March only add to the electoral tension. Mrs. May’s statement that “enough is enough” and that Islam is compatible with Western values only reveal the chasms of willful ignorance or naïve optimism of Britain’s (and Europe’s) political elite.

Homeland security is only one of the many issues Britain shares with America. Deficits and debt, healthcare and other welfare emoluments — all will influence voters come election day.

Trade is not least of them. Donald Trump campaigned for the presidency on the vow to fight currency manipulators and unfair trade deals. Yet the country is no nearer opting for the sound currency. Tax policies that favor large corporations and small businesses alike are the declared policy, but are not yet fully formed as bills before Congress.

President Trump has vowed that a trade deal with Britain is top of mind. Good news for Theresa May, whose 20-point lead when the election was announced has dropped to 1-point according to week-end surveys. Brexit steadfastness may be her best chance of electoral success and principled Tories are dismayed by the party’s left-of-center manifesto. British historian Andrew Roberts calls it an attack “at the philosophy of Toryism in a way that would have left Stanley Baldwin, Margaret Thatcher and Lord Salisbury reeling” with a “programme of social engineering” that “would have left aghast ‘wet’ Tory Premiers such as Churchill, Macmillan and Heath.”

Still, campaign u-turns on NHS services and hostility toward wealth-creators and individual initiative have caused Mrs. May’s fortunes to tumble while, having no where to go but up, bolstered by a platform of popular hand-outs, Mr. Corbyn’s have rebounded.

The abiding question in my view is the freedom of the British people. As Sir Roger Scuton said in relation to Brexit, “It is about the happiness and cohesion of our nation, and the civilization of which we have been, in Europe, the prominent guardians. The true argument is not that it is economically advisable to reclaim our sovereignty, but that it is our moral duty to do so.”

The Conservative government’s own muddled approach to Brexit does the independence movement no favors.

Mr. MacLean blogs for the Disraeli-Macdonald Institute.