GLASGOW, Scotland » "Scotland has gone mad," wrote Chris Deerin, a Scottish columnist, trying to comprehend the surge of nationalism only seven months after an independence referendum was soundly defeated by 10 percentage points.

"It’s a strange thing, starting to think that your homeland may be a bit dim," he wrote in a column for CapX, produced by a research institution of the center-right. "It’s even stranger when that homeland is Scotland, cradle of the Enlightenment, engine of the Empire."

The judgment is harsh, but the sea change in Scotland is one of the great dramas of the British election on May 7, coupled with the collapse of the Liberal Democrats and the rise of the U.K. Independence Party. If some Liberal Democrats are heading toward Labour, Scottish Labour voters are flooding to the Scottish National Party, which looks likely to win most of Scotland’s 59 seats, putting new momentum behind the uncosted notion of independence.

Even Glasgow, heartland of the Scottish Labour Party, is turning to the more fervently left-wing SNP. According to constituency polling, the head of the Scottish Labour Party, Jim Murphy, could lose his seat, along with the shadow foreign secretary, Douglas Alexander.

A wipeout in Scotland could cost Labour leader Ed Miliband a place in Downing Street or force him into a deal with the SNP. And as exciting as all this may be for the Scots, it raises new doubts about the future of Britain.

A Scotland so dominated by the SNP would mean that Labour becomes just another English party, like the Conservatives. Since the SNP’s prime goal is independence, other Britons question whether Scotland should continue to benefit disproportionately from the wealthier south.

England funnels money north that pays for free university tuition and prescription drugs for Scots — benefits not available to other Britons.

Because of a regional formula, Scotland spends 10 percent more per capita than the British average. According to projections from the Office for Budget Responsibility, Scotland’s net fiscal deficit will be 8.6 percent of gross domestic product, compared with 4 percent for Britain.

That doesn’t matter in a unified country, but it will if the SNP acts too purely in Scotland’s interests or presses its Scottish rival but putative Westminster partner, Labour, too hard for new spending.

The SNP leader, Nicola Sturgeon, has impressed the rest of Britain in televised debates. She demands an end to austerity but is vague on how to finance it or reduce the deficit. Nor does she address collapsing oil prices, which would put another big hole in an independent Scotland’s revenue. But as Scotland’s first minister, she’s not even running for a seat. Her predecessor, Alex Salmond, is, however, and they want to force any Labour government sharply left.

Such talk pleases the Conservatives, who argue that a Miliband government dependent on the SNP means "chaos" and "economic irresponsibility." Boris Johnson, a Conservative, compared Sturgeon and Miliband to a scorpion on the back of a frog.

Then the famous "West Lothian question" becomes more acute — why should Scottish members of Parliament vote on matters affecting England, while Westminster politicians have no vote on Scottish matters? Those decisions are made by Scotland’s increasingly powerful regional government, run by the SNP.

With England representing 85 percent of Britain’s population, the Tories have already raised the question of "English votes for English laws." Taken to its logical conclusion, that would mean separate parliaments.

The journalist Martin Wolf wrote in The Financial Times that the SNP as a "permanent kingmaker" risks "the stability of the union."

For "a party interested mainly in having its cake and eating it" to hold the balance of power, he said, "does not seem to me a price worth paying for the union."

Steven Erlanger, New York Times