The British Labour Party leader, Jeremy Corbyn, trod carefully last week.

Re-elected with an overwhelming mandate – almost 62% of the vote – Corbyn had to give a speech to the party conference in Liverpool that would convince moderates that there was still a place for them in the party and reassure the left that he was not about to sacrifice their interests in the name of party unity.

Corbyn largely achieved his aim. But his speech also magnified the crisis facing the party.

Over the past year Labour has torn itself apart over doctrine and direction, but finds itself where it was last September: divided and out of power.

To explain the crisis, it helps to understand the Labour Party.

Since its formation in 1900, the party has been ideologically complex.

Labour is a center-left political party, but it is also a movement that represents diverse left-wing interests: pro-market social democrats, unions, co-operative societies, middle-class reformers, socialists, and other assorted interest groups.

Corbyn has been associated with the left of the party since becoming an MP in 1983. MPs - the Parliamentary Labour Party (PLP) – firmly rejected his candidacy in 2015 and 2016. Corbyn became leader by building a broad coalition that sidelined moderates.

MPs worry that Corbyn is making the party unelectable.

His proposals for an array of interventionist economic policies contrast sharply with the pro-market ideas of the Tony Blair administrations.

Corbyn faced rebellions in the PLP over his opposition to air strikes in Syria and to Trident, Britain’s nuclear deterrent. He is perceived as soft on terrorism, a position not helped by his one-time description of members of Hezbollah and Hamas as “friends.” Corbyn was slow in offering a full-throated condemnation of the anti-Semitic abuse directed toward Jewish party members and MPs supportive of Israel by a tiny minority of his grassroots allies.

But the breaking point for many MPs was Brexit.

Brexit occurred because voters in Labour’s electoral heartland – the industrial regions of the Midlands, NE England, and Wales – overwhelmingly chose to leave the EU. Voters blamed their economic insecurity on the EU’s free movement of labor policies. They were wrong, but this case was poorly made.

MPs suspected Corbyn of sabotaging the EU referendum. Labour was pro-EU, but Corbyn was skeptical, perceiving it as a club for bankers and businesses. Only after becoming leader last year did he publicly support Britain remaining in the EU.

He needn’t have bothered.

Corbyn barely campaigned. He refused to appear at Remain events, while his allies deleted pro-EU language from his speeches and public statements. A firmer pro-EU stance might have swung traditional Labour voters.

Labour MPs revolted. The Shadow Cabinet resigned en masse. 172 out of 230 MPs expressed no confidence in their leader.

So why didn’t Corbyn step down? Bizarrely, a leader who loses the confidence of the PLP is not required to resign. It was always assumed they would.

Is Corbyn to blame for the crisis in the party though?

Just over a decade ago, Labour had won an historic third election in a row. The reformist, pro-business policies of Tony Blair and Gordon Brown had popular support. But today, Blair is reviled as a warmonger and a capitalist stooge. The Chilcot Report into the Iraq War gives the first charge merit. The second is nonsense.

The Blair governments did embrace globalization, business, and the financial sector, but until 2007, Britain’s economy grew rapidly. More importantly, rising tax revenues paid for redistributive tax credits and necessary investments in the NHS, education, and the welfare system.

This legacy was not built upon.

Iraq fatally damaged Blair’s standing, while reformist MPs divided into squabbling factions. The PLP grew disconnected from voters. In 2015, Scottish Labour voters, furious at years of neglect, defected to the Scottish National Party. In NE England and the Midlands, traditional Labour voters have begun migrating to the UK Independence Party.

Moderates can whinge all they like, but the fact that an obscure socialist now leads them is an institutional failing.

One worry is that the party will split. Last week, Corbyn had to remind his party to fight the Conservatives, not each other.

The party has split twice before, in 1931 and 1981.

In 1931, under pressure from the banks, the Labour government of Ramsay MacDonald tried to make up a budget deficit through spending cuts, reductions in benefits, especially unemployment insurance, and tax rises. The cabinet failed to agree to these proposals.

The pound collapsed. So did the government.

MacDonald and his allies formed a National government with the Conservatives and Liberals. Labour took the blame for the crisis and for the subsequent withdrawal of sterling from the Gold Standard. In the 1931 general election Labour representation fell from 277 MPs to just 52.

In 1981, the party split again. Alarmed at the leftward drift of the party, moderate MPs formed the Social Democratic Party. Following a catastrophic defeat in the 1983 election, Labour began a slow process of change. A new leader, Neil Kinnock, gradually moved the party to the center, expelling radicals and promoting reformers like Blair and Brown.

A split would be unwelcome. In 1931 and 1981 it took the party a decade and a half to regain power.

Labour governs successfully from the center. The welfare state constructed by the 1945-1951 Labour governments was part of a larger system of “managed welfare capitalism,” which encompassed Liberal social reformism, Keynesian economics, and lessons learned from WWII economic planning. Tony Blair constructed a centrist coalition that aligned the interests of moderate Labour voters with those of moderate Conservatives alarmed by increasingly right-wing Tory economic and social policy.

But perhaps the center is moving.

The Conservative Prime Minister, Theresa May, is moving onto Labour’s economic terrain, promising much needed infrastructure investment, joint worker-management boards, tighter corporate governance, and restrictions on foreign takeovers. She has also promised that Brexit will not undo workers rights enshrined in EU law.

Corbyn might be onto something after all.