There’s a reason capitalist management loves to squeeze its employees, and Bernie Sanders might be learning a little about that these days.

The Democratic Socialist’s campaign—which became the first to unionize this Spring—is spending nearly two million dollars a month on salaries, payroll taxes, and insurance.

That amount is only rising, as the campaign is adding organizers in early-voting states. Even at the lowest positions, they will earn the equivalent of $15 per hour with generous benefits, thanks to recent labor negotiations.

That wouldn’t be a problem, if the campaign was taking in $10 million a month, as it did throughout the second half of 2015—let alone the wild multiples of that at the height of Berniemania in early 2016.

Instead, contributions have been coming in at just $6 million a month. That’s far more than most of the competition, but will restrict the campaign’s growth going forward if the pace doesn’t pick up.

The heavy spending on payroll pre-dated the early May ratification of a collective bargaining agreement (CBA), or even the March establishment and recognition of the union, which includes staffers below the level of deputy director.

Shortly after announcing his second Presidential candidacy, on February 19, Sanders began loading up on high-salaried positions.

As of the end of June, Sanders was paying 263 salaried employees an average of more than $2000 per two-week payroll period. At the end of September 2015, with more money coming in, fewer than two dozen staffers were earning that much.

The generosity—or top-heaviness—stands in contrast with the Warren campaign.

Although the two campaigns spent roughly the same on payroll over the three month period, of April through June, Warren used 20 more staffers, all told, than Sanders. More than twice as many Sanders staffers than Warren staffers were paid $20,000 over those three months—the equivalent of $80,000 annually—with 14 on the Sanders team topping $25,000, compared with just two on the Warren campaign.

The CBA is raising benefit costs for the campaign, while restricting hours that some salaried employees work. Ratification had an immediate cost as well: in the very next payroll, distributed in mid-May, some 80 campaign employees—out of about 120 at the time—received a ratification bonus, confirms campaign communications director Adrianna Jones.

Most received around an extra $600, for a total of more than $50,000 to the campaign (not including any additional payroll taxes incurred).

Last week the Washington Post reported that the union was pressing for higher pay and improved benefits for the field organizers being hired and deployed in early-voting primary and caucus states. They couched the request in the light of the Senator’s very public support for high wages and benefits, including a $15 per hour minimum.

Top campaign officials find themselves in the awkward position, the Post revealed, of embracing some of the most cliched capitalists’ arguments: they can’t afford to raise those salaries, they say, because the organization has already made hiring decisions based on budgets assuming the current pay levels.

That impasse has been crossed, in part by the campaign agreeing to limit the number of hours those field organizers work. That will ensure that their salaries work out to $15 per hour. However, it might necessitate the campaign hiring more of them.

Julian Castro and Elizabeth Warren have also recognized unions established by their campaign staffs. Both are still negotiating their collective bargaining agreements.

The outcome of Warren’s agreement could have particular ramifications, as her employee costs are already high.

The irony will not be lost on Republicans, if payroll costs ultimately impede the campaigns of the two candidates most dedicated to workers’ rights and protections.

Or, perhaps those very campaigns will prove that well-treated workers produce the best results for an organization. That’s certainly what they’re hoping, even if it makes for difficult choices at budget meetings—and maybe even an occasional dark desire to be more like those ruthless capitalists.