The wonderful thing about elections is that they end with a decision. The divisions remain. But for the time being, the question of who governs is settled.

This year’s United States presidential election is on course to be an exception. Even if Mrs Hillary Clinton wins the US electoral college by a big margin, hers would be the most grudging landslide in history.

A large chunk of Americans will be receptive to Mr Donald Trump’s claim that the result was rigged. Many of Mrs Clinton’s voters will have backed her only reluctantly on the grounds that anything would be better than Mr Trump.

She will enjoy no honeymoon. Speculation about a one-term presidency will begin almost as soon as she takes office.

Anyone who doubts this should remember President Barack Obama’s fate. Now on the home stretch to retirement, he has spent the past six years failing to persuade a hostile Congress to act. From annual budgets to early-learning legislation, almost all of his efforts have come to naught.

His biggest legacies — healthcare reform and Wall Street regulation — came within his first two years, when he had a Democratic majority. Even now, Republicans vow to repeal both laws at the first opportunity. This year, Mr Obama has been unable to push through even emergency help for areas affected by the Zika virus and a modest tightening of gun safety checks following a series of massacres. That is without facing re-election. What chance would Mrs Clinton have?

The answer depends on two things. The first is whether Democrats can regain control of Congress in November.

There is a good chance they can recapture a thin Senate majority — somewhere around 51 seats to 49. But taking the House of Representatives is a taller order. The chances that Democrats can regain both chambers, a prerequisite for governing in today’s climate, are thus slim.

The second is how Republicans interpret a defeat for Mr Trump. Would they recognise the time had finally come to turn the party into a demographic big tent?

If so, Mrs Clinton may be able to find enough middle ground to push through big changes, such as tax reform and an immigration overhaul.

Or would the hardline conservatives, led by Mr Ted Cruz, the Texan senator who gave Mr Trump the biggest run for his money in the primaries, see a chance to resume Tea Party-era congressional brinkmanship? In that case, Mrs Clinton’s agenda would stand little chance of daylight.

My money would be on the latter. To be sure, a big Trump defeat would embolden pragmatic Republicans to warn about their party’s fate in California, which is now in a permanent minority in a state with a non-white majority.

California’s present is America’s future. What happened there could prefigure the national Republican party’s decline.

But that is the point reformers made after the party’s last defeat in 2012, when they urged it to cease the intolerant rhetoric about gay people and women’s reproductive rights and extend an olive branch to Hispanic Americans.

The party’s grassroots were obviously unswayed by the autopsy, since it nominated Mr Trump.

It is hard to see how Republican pragmatists would be able to convince an embittered Trump base, which believed Mrs Clinton had stolen the election, to abandon its strongest beliefs. Mr Cruz, on the other hand, is too clever a politician to ask them to do that.

A Trump defeat would sharply improve his chances of winning his party’s crown in 2020. For anyone who is sick of America’s permanent election, I have some discouraging news: It really is permanent.

The next cycle has already begun. The opening shot was at Mr Trump’s convention in Cleveland, in which Mr Cruz refused to endorse the Republican nominee. Instead, he urged an almost unanimously booing hall to “vote your conscience” in November.

Mr Cruz’s non-endorsement of Mr Trump was dramatic political theatre. With the hindsight of a Trump defeat, it will start to look prescient — even courageous — just as Mr Cruz intended.

Mr Cruz has a head-start on his potentially biggest rival, Mr Paul Ryan, speaker of the House of Representatives, whose timid attempts at legislative compromise with Democrats have caused him to lose his halo among conservatives.

Mr Cruz will also have an edge on Mr Marco Rubio, the Florida senator, whose chances of re-election in November are touch-and-go.

Either way, the contest is in motion. Being nice to Mrs Clinton will be held up as a disqualification. Blocking her initiatives will be seen as a credential. By large margins, Republican voters say Mrs Clinton is dishonest — as do a minority of Democrats.

In time, all political trends come to an end. Unfortunately for Mrs Clinton, America’s deep polarisation — and the breakdown of the Republican party — has yet to run its course. Mr Trump’s nomination has probably extended the agony.

Since he has adopted unorthodox positions, including support for current levels of social security and Medicare spending, conservatives will be able to say: “I told you so: We strayed from our principles by nominating an immoral big spender from New York.”

That will be Mr Cruz’s pitch. It will also be Mrs Clinton’s bane. Whether she wins small or big, she will inherit a poisoned well. FINANCIAL TIMES

ABOUT THE AUTHOR:

Edward Luce is the chief US columnist at Financial Times