The past five years saw the rise of two dynamic, unprecedented, and astonishingly successful experiments in left electoral politics. The last four months have seen both come to tragic ends.

In December, despite a remarkable result only two years earlier, Jeremy Corbyn’s Labour Party was routed in a general election dominated almost entirely by the cul-de-sac of Brexit. This week, despite coming closer than ever to victory, Bernie Sanders suspended his second campaign for the Democratic presidential nomination. Faced with this state of affairs, despondent socialist movements in America and Great Britain are now left to pick up the pieces — political, emotional, and otherwise — and carry their projects into a future at once perilous and uncertain.

For some, recent events will be a reason to withdraw or disassociate from meaningful engagement with politics. For others, they will resurrect all-too familiar debates about the utility (or, as some would have it, futility) of electoralism. Both impulses are, albeit in varying degrees, understandable but wrongheaded. Withdrawal from substantive political engagement, whatever form it ultimately takes, may be a balm against future disappointments but is self-defeating for transparently obvious reasons. As for the old debate about parliamentary versus extra-parliamentary organizing, the standard cliché remains apropos: the two aren’t mutually exclusive, and abdicating responsibility for the former would be a peculiar reaction to the failure of two left projects that came so maddeningly and heartbreakingly close to transformative electoral success.

Wherever we go from here, and whatever strategic tweaks are made along the way, the Sanders and Corbyn experiences represent remarkable case studies in the value of left engagement with mainstream politics — and a cautionary tale about the obstacles we face to success.

Their different personal styles notwithstanding, the two have much in common and their respective projects faced many of the same difficulties. Both were ideologically committed socialists whose careers had mostly been spent doing the thankless work of dissent within a political climate growing ever-more hostile to socialism. Both were compelled to operate within the confines of traditionally working class–based parties hollowed out during the neoliberal moment of the eighties and nineties but still possessed of a residual and demoralized working-class constituency. Both are fundamentally decent men who rarely found their personal temperaments an asset when dealing with opposition from within their own parties (Corbyn’s preference for conciliation in particular would ultimately prove a tragic flaw).

Both took the Left further in electoral terms than anyone thought was possible but were impeded by entrenched establishments who viewed them less as adversaries than as menacing interlopers to be defeated at all costs.

For Sanders, this meant the unprecedented consolidation of electoral rivals ahead of a pivotal Super Tuesday vote he was hitherto on course to win — engineered by party grandees and enabled by a media determined to shut out and marginalize his campaign while boosting his opponents. For Corbyn, as we’ve long understood but now know officially thanks to a recently leaked report, it meant a treasonous campaign of sabotage undertaken by key figures within the Labour Party who actively worked to prevent it from winning the 2017 general election.

While both were certainly feared and hated by traditional conservatives, the force that ultimately hindered their efforts came not from the Right but rather from what is still, albeit with increasing absurdity, known as the center-left: that is, from people who might broadly be called liberals in the post-1970s sense of the word. Though arguably weaker and more ideologically exhausted than at any point since its zenith in the 1990s, this strand of market centrism still dominates the nominal “left” in many national party systems and, perhaps more importantly, its adherents mostly retain control of the levers of power in individual party apparatuses even when their ideas are discredited or their dreadful campaigning bungles winnable elections (as in 2016).

This peculiar combination of weakness and strength is the paradox at the heart of modern liberalism and the vulnerability both Corbyn and Sanders were nearly able to exploit. Had either succeeded in transforming their respective parties and winning power on the popular programs they championed, the undead center-left that has carried on in zombified form since the financial crisis of 2008 might finally have been buried for good. Alas, the task remains incomplete and the enervated neoliberal project continues to hold the reins of what is nominally the reform-minded electoral alternative to conservatism in the United States and the United Kingdom.

The Left should not be content with this state of affairs.

Insofar as it still has a coherent objective that can be articulated, liberalism seeks not so much to humanize capitalism as it is to give capitalism a human face — that is: to provide a facade of inclusion and shared prosperity while fundamentally protecting the role of markets and the positions of their greatest beneficiaries. It is now, more so than at any point in its long history, a set of hollowed-out dogmas and unthinking reflexes without a real program or political imagination; so interwoven with wealth and celebrity it now sees them as ends in themselves.

That millions of ordinary people beset by declining living standards, weakened welfare states, increasing corporate incursion into daily life, and a planet growing less inhabitable by the day are routinely compelled to cast votes for people who do not represent them — be they neoliberals or formations on the nationalist right — is a predicament no socialist or small-d democrat should be willing to accept. Ultimately thwarted by the liberal center, neither Sanders nor Corbyn succeeded. But their efforts revealed the widespread appetite for a genuine alternative to neoliberalism and underscored the utility of leftist involvement in mainstream politics.

Whatever lies ahead in the wake of their respective defeats, and whatever insights the inevitable debates ultimately yield, socialists must be resolute and hard-headed about the difficult and necessary task before us when it comes to future electoral engagement: to challenge the neoliberal center with the goal of supplanting its position of political and cultural leadership and winning state power, with all its difficulties and limitations, to secure maximum gain for the ordinary citizen in late capitalist society and the redistribution of wealth and power from top to bottom. There is no alternative.