Sensible politicians in Britain and the United States have encouraged their fringe supporters for too long.

America’s Republican Party could suffer the same fate as Labour in the United Kingdom next year if a far-right populist like Ted Cruz or Donald Trump wins its presidential nomination.

This website doesn’t believe either Cruz or Trump will triumph in the primaries. But they do command the admiration of a sizable segment of the Republican Party and that is in itself startling.

For neither Cruz nor Trump represents a serious governing philosophy. The former maintains that the only reason Republicans have been losing presidential elections is that they keep nominating candidates who aren’t right-wing enough. The latter claims that leaders in both parties have conspired to weaken America and only bravado and political incorrectness will somehow make the country great again.

Polls show nearly one in two Republicans agree with one or the other.

Moderate connivance

Their delusions echo across the Atlantic where Britain’s Labour Party recently elected as its leader a Marxist and peacenik: Jeremy Corbyn.

Like Cruz and Trump, Corbyn assures his supporters that there is nothing wrong with their platform. They didn’t lose the last election because — as all the experts and polls told them — their policies were seen as too left-wing; they lost, Corbyn insists, because Labour wasn’t “principled” enough.

Sounds familiar?

Most lawmakers know this is nonsense. Only a handful supported Corbyn for the leadership; the majority recognizes that Labour must be credible if it is to defeat the Conservatives in 2020. But they won’t speak out because they fear reprisals from the far left that now controls their party.

If Labour isn’t trusted by voters, it is partly the moderates’ own fault, though.

Janan Ganesh argues in the Financial Times that they for too long connived in the very style of politics that now engulfs them.

They impugned the motives of Conservatives, often reading malevolence into policies even as they grudgingly copied them (there is no hatred like self-hatred). They seethe when they are called Tory because, to them, the name really does connote inherent vice.

This website has reported on some of the worst examples: a lawmaker accusing the ruling Conservatives of not caring about child poverty; Andy Burnham, one of the party’s leadership contenders, blaming the right for “terrorizing disabled people” by planning to overhaul their benefits; and Corbyn himself, the man who defeated Burnham to become leader, insisting that the Conservatives are only interested in “driving down wages, cutting taxes for the wealthiest, allowing house prices to spiral out of reach, selling off our national assets and attacking trade unions.”

Ganesh adds the incessant Labour scaremongering about the National Health Service. The left never stops pretending it is “only ever hours away from a vindictive privatization,” he writes, even though the Conservatives have run it for most its existence.

If all Labour says about the Conservatives were true, British voters, who keep electing them, must be cruel bunch.

Moral arrogance

“Some of this is the sheer sport of politics,” Ganesh admits. “Some of it is more than reciprocated by Conservative blowhards.”

But there is also a unique moral arrogance on the left that has slowly blinded Labour to the concerns of middle-class and moderate voters who most of the time determine the outcome of national elections. Hence it lost in both 2010 and 2015.

Ganesh argues that Labour’s mainstream is now “victimized by the same culture of invective and moral invigilation” it tolerated for years. It has itself become the purists’ latest target.

He could make the same argument about America’s Republicans.

Politics of division

Edward Luce writes in the same newspaper that conservatives in the United States “do not just disagree with President Barack Obama — they hate him profoundly.”

When asked if they would back a Donald Trump nomination, even the most moderate Republican says anyone would be better than this “feckless, weakling” president, to quote Chris Christie, the New Jersey governor.

The Atlantic Sentinel has argued the same and we cautioned that while the politics of division and fear may work for Republicans in the short term, as it resonates with hard-right voters who are most likely to vote in the presidential primaries, it is going to cost them dearly in the general election next year against Hillary Clinton.

As with Labour in the United Kingdom, the mainstream of the Republican Party has not only tolerated its most reactionary elements for years; it has actively encouraged them in their illiberalism to pry white working-class voters away from the Democrats.

Luce faults Democrats for making little effort to understand why these Americans have drifted away from them and instead dismiss them as simply bigoted.

But to the extent that there really is bigotry on the right, Republicans who should know better have made it worse.

Bloomberg View ‘s Jonathan Bernstein argued earlier this year that from Joseph McCarthy to Richard Nixon, Spiro Agnew to Newt Gingrich and from Sarah Palin to Ted Cruz, conservative leaders have told their voters for decades to trust in easy answers and believe that the normal frustrations of politics and international relations are the product of villains, collaborators and fellow travelers.

And, of course, they succeeded in convincing many Republican voters that any conservative politician who engages in the norms of democratic compromise is a traitor to the cause.

Now this demagoguery has finally come back to bite them in the form of Donald Trump.

Elections are still won in the center

Like Labour, Republicans have raised the stakes of politics beyond reason.

As Ganesh puts it, “The reality of politics in a rich, modern country is that parties are squabbling over marginalia.”

Sullying someone’s character because he sees no role for local government in the oversight of state schools suggests a shortage of perspective.

For purists like Corbyn and Cruz, politics is a titanic struggle between good and evil.

Yet nearly every election confirms that the vast majority of voters in both their countries is far more reasonable and pragmatic.

This website has advised Republicans to remember that it are moderate and middle-income voters in swing states like Florida, Ohio, Pennsylvania and Virginia who will help them win in 2016 — or not.

These voters do not generally care much about culture wars or tax cuts for their bosses. They are worried about keeping their jobs, about a lack of real wage growth, about being able to send their kids to college and pay for the family’s health insurance.

Those are the issues foremost on the minds of most voters in most Western democracies. Political parties win if they understand these problems — or are at least perceived as understanding them — and have sensible policies to address them. They lose if they are beholden to the crazies in their midst and vacate the center ground.