WASHINGTON — Donald Trump won fair and square and, as Hillary Clinton said in her concession speech, is owed an open mind and a chance to lead. It is therefore incumbent upon conservatives (like me) who have been highly critical of Trump to think through how to make a success of the coming years of Republican rule.

It begins by recognizing Trump’s remarkable political instincts. As Paul Ryan noted in his morning-after olive-branch news conference, Trump heard “a voice out in this country that no one else heard.” Trump spoke to and for a working class squeezed and ruined by rapid technological and economic transformation.

One of the principal tasks for the now-dominant GOP is to craft a governing agenda that actually alters their lives and prospects. In the end, it was this constituency of those left behind by the new globalized digital economy that delivered the presidency to Trump.

Nonetheless, this election was not just about the social/economic divide. It was also about the ideological divide between left and right. The most overlooked factor in the election is the continuing deep and widespread dissatisfaction with Obamaism.

It tends to be overlooked because President Obama remains personally popular (56 percent in the latest Gallup). As a charismatic campaigner, whenever his name is on the ballot, he wins. But when it’s not — 2010, 2014, now 2016 — the Democrats get shellacked.

The reason is no mystery. The problem was never with Obama himself, but with his policies. Before each of those losing elections Obama would campaign saying that his name wasn’t on the ballot but his policies — and now his legacy — were. The voters made clear what they thought of his policies and legacy.

Simply put, from the beginning of his presidency, Obama overreached ideologically, most spectacularly with his signature legislative achievement — Obamacare. The spike in Obamacare premiums and deductibles just two weeks before Tuesday’s election proved a particularly damaging reminder of what Obamaism had wrought.

Hence the other principal task for the now dominant GOP: Undo Obamaism. Begin with canceling Obama’s executive orders on everything from immigration to climate change. Then overturn his more elaborate legislative adventures into overweening liberalism, starting, of course, with Obamacare.

The promise of a Trump presidency is that, if it can successfully work with a Republican Congress, it could turn Obamaism into a historical parenthesis. Republicans would then have a chance to enact the Reaganite agenda that has been incubating while in exile from the White House.

For years Washington gridlock has been attributed to GOP obstructionism. On the contrary, serious legislation, such as Medicare reform passed by the GOP House, was either strangled in the Senate by Democratic leader Harry Reid or died by veto on President Obama’s desk.

Beyond the undoing, there’s now the prospect of doing. Serious border enforcement, including a wall, for example. That’s not only a good in itself, it would offer leverage in a grand bargain that would include eventual legalization of resident illegal immigrants, an idea supported (according to the exit polls) by more than seven in 10 voters.

Another given is a reshaping of the currently rudderless Supreme Court with the nomination of a conservative justice to replace the late Antonin Scalia.

During the campaign, Trump’s populism often clashed with traditional Reaganism. The key to GOP success is to try to achieve an accommodation, if not a fusion. Two agendas: one ideological, one socioeconomic. They both need to be addressed. Onto the Reaganite core of smaller government and strict constitutionalism must be added a serious concern for the grievances of the constituency that animated the Trump insurgency, the long-suffering, long-neglected working class.

If Reaganite conservatives want to head off wrongheaded solutions — such as massive tariffs, mercantilist economics and trade wars — they must be prepared to accept such measures as federal wage subsidies and targeted restraints on trade. This involves giving up a measure of economic efficiency. But the purpose is to achieve a measure of social peace and restore dignity and security to a stressed and sliding working class. Some might even call it compassionate conservatism.

The key to success for a Trump presidency is for the Reaganite and populist elements in the party to be willing to advance each other’s goals even at the cost of ideological purity. This will require far-reaching negotiations between a Trump White House and a GOP Congress. The Republicans have gained control of all the political branches. They have the means to deliver. They now have to show that they can.

Charles Krauthammer’s email address is letters@charleskrauthammer.com.

(c) 2016, The Washington Post Writers Group