The Democratic Party is sharply divided — and the political consequences of the divisions are about to change dramatically.

The lack of a consensus in the party was an enormous benefit in the 2018 midterm elections, allowing democratic socialists to run in solidly blue districts and more conservative Democrats to challenge Trumpified Republicans in red and purple regions. But that divide-and-conquer path to electoral victory will no longer work when the party needs to settle on a single ticket with a set agenda heading into the 2020 general election.

What will that agenda be? Will the candidate who emerges from the scrum of those competing for the Democratic nomination be a bold and ambitious progressive proposing to tame economic stratification by raising taxes on billionaires, launching a Medicare-for-all program of universal health insurance, offering free college tuition, and confronting climate change with a Green New Deal? Or will the Democratic standard-bearer be a sober-minded centrist peddling a long list of "honest," "achievable," and "realistic" programs designed to help "average families" while also avoiding "unrealistic ideological promises"?

Will the party's ideological lode-stars be Sen. Bernie Sanders (I-Vt.), Rep. Alexandria Ocasio-Cortez (D-N.Y.), and others of the populist left? Or is Nancy Pelosi setting the future direction for the party in pushing a fiscally prudent rules package on her very first day as speaker of the House that will hamstring progressives by requiring spending increases to be offset by mandatory spending cuts or tax hikes?

Those will be the options before Democratic voters a year from now.

In some ways the dispute is less fundamental than the one that divides the Republican Party. The two GOP factions disagree about the character of the United States and the world itself. Is the U.S., as the president and his supporters believe, a closed nation ringed by walls and locked in zero-sum competition with the other nations of the world? Or are we, as Sen. Mitt Romney and other part-time refuseniks from the pre-Trump Republican establishment insist, an open society and "leader of the free world" working in concert with allies to defend a "liberal international order" of our making and from which all well-meaning nations clearly benefit? The GOP's sharpest policy divides — over immigration and trade — follow from this bedrock philosophical disagreement about the country and the world.

Democratic disagreements are less about ends than they are about means — though that doesn't make the clash any less rancorous. Both want a society marked by fairness, but they disagree about how to get there.

For centrists, government's role is to tidy up some of the negative externalities generated by globalized markets and economic growth but never to become an impediment to them. It's the markets and the growth that generates the rising tide of wealth that raises most boats and that government modestly redistributes to give a boost to the few left behind. The key is to find the right balance: Too little government and the losers suffer; too much government and the winners generate less wealth and everyone suffers. When a balance is struck, we're all better off, with progress maintained and fairness achieved.

The left-wing populists view things differently. They believe that the centrists are far too inclined to follow Republicans in fetishizing markets and growth. In the process they fail to reckon with the income stratification and economic inequality produced by the policies of the past 40 years. The rich have gotten ever-richer while everyone else has stagnated or fallen behind. Reversing course will require far more than enacting a laundry list of policy tweaks. It will require a significant shift of direction and priorities — including a return to the higher tax rates that prevailed before the Reagan Revolution, significant cuts to defense spending, and several major new government programs to level America's highly stratified playing field.

Should Democrats be pragmatists or break from the status quo? Should they tinker at the margins of the market economy or declare that the era of big government is back? Those are the questions confronting Democratic voters over the next two years.

Some of the candidates will seek to build on the centrist legacy of Bill Clinton and Barack Obama. Others will propose a return to the audacious ambition and experimentation of FDR. Still others will aim to blur the distinction between the alternatives, portraying themselves as all things to all Democrats. But there will be no way to avoid the decision entirely.

Just as the Republican Party has been waging a civil war about whether it will stand for or against nationalism, so the Democrats need to decide whether and to what extent they want to continue serving as handmaidens to free-market capitalism.

Nothing less than the soul of the Democratic Party is at stake.