In a crowded primary stacked with candidates who are driving their party further left, Bernie Sanders is no longer the progressive alternative. Instead, he’s just another candidate.

For a long time, Sanders had been the Democratic Party’s outlier. A party independent who described himself as a socialist going back half a century, Sanders was the Democrats’ political headache in 2016, running a bombastic presidential campaign against an out-of-touch, stagnant Democratic establishment.

But that fervent appeal was notably absent from last night’s primary debate. Sanders faded into the background as younger candidates, like Sen. Kamala Harris, D-Calif., dominated the stage and articulated the policies that once set him apart. To name one example, Sanders' signature program of “Medicare for all” has been endorsed by the large majority of Democratic candidates in one form or another.

This progressive shift owes much of its success to Sanders. He proved that revolutionary, fringe positions can and will be accepted by voters, regardless of the establishment’s reaction. And as a result, the Democratic Party looks more like Rep. Alexandria Ocasio-Cortez, D-N.Y., than House Speaker Nancy Pelosi, D-Calif., who was herself considered pretty far-left as recently as 2010.

But Sanders’ entry into the mainstream bodes ill for his presidential campaign. He’s still second-best, polling behind Democratic front-runner Joe Biden, the moderate alternative. But Sanders’s performance in last night’s debate is proof that, despite his conviction, Sanders’ campaign lacks the momentum it once had.

The Democratic candidates will continue to rhetorically move further and further to the left as this election cycle wanes. In a tight race that’s primarily focused on opposition to President Trump, the candidates will accept and propose policies that ideologically confront Trump and the GOP. The more progressive the policy, the less like Trump it sounds.

This doesn’t appear to be a winning strategy, considering that 35% of Americans consider themselves conservative, 35% claim to be moderates, and only 26% call themselves liberal, according to a recent Gallup poll. Each of the Democratic candidates on last night’s stage falls within that 26% camp.

And then there’s the issues: More than 70% of Americans with private insurance are satisfied with their health plans, and 71% of Americans say the economy is very or somewhat good, according to a CNN poll. Every candidate on stage appeared oblivious to these realities. Likewise, on immigration, voters prefer Trump’s hardline policies to Democrats’ effective demand for open borders and zero deportations.

In their race to the White House, the 2020 Democrats are loath to let anyone get to their left — even Bernie Sanders. This means that ideologically, Sanders has won, but the ever-advancing socialist Democratic Party is leaving him and his campaign behind.