Vermont Sen. Bernie Sanders isn’t holding back his thoughts on why Democrats still haven’t come to an agreement on their $3.5 trillion social-spending bill. In a recent opinion piece, he unleashed on lobbyists and billionaires who oppose the spending.

“The corporate elite seem to love the idea that billionaires have a lower effective tax rate than nurses or teachers and that, in a given year, there are dozens of profitable corporations that don’t pay a nickel in federal income tax,” Sanders wrote in an op-ed for Fox News.

Sanders has also recently criticized centrist Democratic Sens. Joe Manchin and Kyrsten Sinema’s opposition to the price tag of President Joe Biden’s $3.5 trillion social-spending package, which includes measures like affordable childcare and free community college. He’s held several press conferences, venting his frustration at the slow movement of a bill he shepherded as chairman of the budget committee. His Wednesday op-ed called for “Democratic unity,” but he wasn’t vague on indicating who he thinks is to blame for the stalling of the package.

Sanders referenced Tesla CEO Elon Musk and Amazon CEO Jeff Bezos as owning more wealth than the entire bottom 40% of the US population and wrote they, along with other billionaires, are “vigorously opposed” to the Democrats’ legislation that would raise the corporate tax rate and hold the wealthiest people accountable for paying their fair share in taxes. 

He also called out lobbyists from the pharmaceutical industry, private health insurance companies, and the fossil fuel industry for persuading some lawmakers to oppose the passage of the bill. Insider reported last week that Sanders accused Manchin and Sinema of selling Biden’s agenda out to Big Pharma,  saying during a press briefing to “take a hard look” at the lawmakers’ campaign-finance reports.

“See where they get their money, how many of them get their money from the pharmaceutical industry, and the executives there,” Sanders said. “And I think there will be a direct correlation.”

Democrats are in the process of negotiating what will make it into the final version of their social-spending bill, and given Manchin and Sinema’s stance they will not support a $3.5 trillion price tag, measures will have to be cut. Insider’s Joseph Zeballos-Roig reported on what those measures could be: free community college, child tax credits, affordable housing, and more. 

But Sanders has remained adamant that Democrats should not cave to what two members of the party want, putting measures like free community college and lower prescription drug prices at stake.

“Will all Democrats stand together to protect the interests of the elderly, the children, the sick and the poor? Will all Democrats stand together to take on the greed of the pharmaceutical industry, the health insurance companies, the fossil fuel industry, and wealthy campaign contributors?” Sanders wrote. “I certainly hope so.”