Joe Biden criticized Sen. Elizabeth Warren’s (D-MA) brand of politics on Tuesday as “elitist” after the progressive firebrand suggested he was running in the wrong party’s presidential primary.

The former vice president, who was once the Democrat frontrunner but has been eclipsed by Warren in recent months, made the comments in a self-published Medium piece titled, “I Have Fought for the Democratic Party My Whole Career.” The piece, although not mentioning Warren by name, set out to repudiate not only her suggestion that Biden should be seeking the Republican nomination but also the “angry unyielding viewpoint” that those who “disagree with you … must be a coward or corrupt or a small thinker.”

“Some call it the ‘my way or the highway’ approach to politics. But it’s worse than that. It’s condescending to the millions of Democrats who have a different view,” the former vice president wrote. “It’s representative of an elitism that working and middle class people do not share: ‘We know best; you know nothing’. ‘If you were only as smart as I am you would agree with me.'”

Biden proceeded to argue such tactics were not conducive to getting “anything done” or building a party that was capable of beating President Donald Trump in 2020.

“I learned a long time ago that if you question someone’s motivations rather than their judgment you get nowhere,” he stated. “It’s hard to get past go if you start off by saying the other person is in the pocket of special interests or is corrupt.”

Despite the pleas for “compromise” and “unity,” Biden spent a good deal of the piece highlighting his own policy prescriptions, many of which are directly in opposition to those being proposed by more liberal Democrats like Warren. In particular, the former vice president touted his proposal for expanding ObamaCare through a public option, which Warren and others have claimed will not be as efficient as Medicare for All.

“I stand with the Democratic Party of Barack Obama — the party that fought for and passed the Affordable Care Act — an historic transformation of our health care system that took a generation to achieve,” Biden wrote. “I’m not walking away from ObamaCare … Maybe others want to walk away from ObamaCare — I don’t.”

The medium piece comes as the Biden and Warren camps have traded barbs back and forth in recent weeks. Biden, specifically, has attacked Warren for lying about how she would pay for her Medicare for All proposal without raising taxes on the middle class. It was in response to such attacks last week that Warren suggested Biden was “running in the wrong presidential primary.” Even though Biden had technically started the altercation, the former vice president’s campaign manager used the opening to attack Warren’s prior Republican affiliation.

Many have noted that the flare-up between the two camps underscores the ideological divisions raging within the Democrat Party at the moment. Biden, who claims to be the only Democrat to win back the white working class, is campaigning as something of a moderate that will bring forth incremental change. The strategy is evident by the former vice president’s policy platform, which is full of ideas that were seen as too radical during the Obama years but are now considered tepid when compared to those advocated by progressives like Sen. Bernie Sanders (I-VT) and Rep. Alexandria Ocasio-Cortez (D-NY). Warren, on the other hand, is a proponent of radical change, as exhibited by her endorsements of a wealth tax and the Green New Deal.

Adding to the antagonism between the camps is the precarious position Biden finds himself in three months away from the first nominating contest in Iowa. Although the former vice president started the race as the clear frontrunner, leading the field by as much as 32 percentage points at one point, his campaign has steadily declined.

Biden’s decreasing political fortunes have comes as Warren’s have only increased. The Massachusetts Democrat has leapfrogged Biden in the early primary and caucus states. One recent poll out of Iowa showed Warren leading the field with 28 percent support among Democrats, while Biden was relegated to fourth place with only 12 percent. A similar situation has played out nationally, by which most polls show Warren leading Biden, albeit with a narrow margin.

As Biden’s campaign spins downward, his attacks on Warren, who many now acknowledge as the frontrunner, have only increased, culminating in his Medium piece on Tuesday.

“I have fought for the Democratic party my whole career. I know what we stand for, who we stand with and what we believe. And it’s not just policies or issues. It’s in my bones,” the former vice president stated. “That’s not something everyone in this primary can say.”