Democratic presidential candidate Pete Buttigieg is not offering healthcare benefits to any of his campaign staff while Bernie Sanders has unionized his team.

Buttigieg is the only major presidential contender to not offer healthcare benefits to his team, an NBC News analysis revealed.

But the South Bend mayor's campaign is giving salaried workers a $400 monthly stipend to buy healthcare, which is enough for a single adult with no children to cover a 'silver plan' through the Obamacare exchanges.

Pete Buttigieg is not offering health care benefits to any of his campaign staff

Bernie Sanders has unionized his campaign team

Treatment of campaign staff has become an issue in the Democratic primary this year.

These kind of behind-the-scene details usually don't get such attention but come in the wake of allegations from women who claimed they were sexually harassed by a staffer on Sanders' 2016 campaign.

Sanders announced this week his campaign staff had unionized and he will pay the entire health insurance premiums of any worker paid under $36,000. The campaign also announced new guidelines around sexual misconduct.

'We have achieved some of the strongest standards for campaign workers in history and set the bar higher for the next generation of campaigners,' Sanders campaign manager Faiz Shakir said in a statement Wednesday.

Other candidates have talked about the treatment of their staff, a move that comes as voters rated in the last election rated health care as one of their top concerns, along with the economy.

Their talk also appeals to the blue-collar voters in the Midwest who helped Donald Trump win the White House in the 2016 contest.

Political campaigns are usually built on the backs of free labor - volunteers putting out yard signs, staffing rallies, and making phone calls in the hopes of making contacts or landing a job in Washington D.C.

Other major presidential contenders offer healthcare options

Elizabeth Warren's campaign has healthcare coverage through United Healthcare while Kirsten Gillibrand's and Beto O'Rourke's have it through Blue Cross Blue Shield. Cory Booker's campaign uses Aetna.

Joe Biden's and Kamala Harris' campaigns told NBC News they are providing healthcare coverage to staff.

Pete Buttigieg and other Democrats are paying their staff a $15 minimum wage

Under Obamacare, employers who have 50 or more full-time employees must offer health care the following calendar year.

Buttigieg's campaign has 49 staffers with plans to keep hiring.

'Crossing this threshold will put us in a position to get a good multi-state group plan, which we are currently negotiating,' Buttigieg press secretary Chris Meagher told NBC.

Julian Castro has vowed to pay all of his campaign staff - even the interns - a minimum wage of $15 per hour.

That amount is what House Democrats want to raise the national minimum wage to be.

Sanders, Booker, Buttigieg, Jay Inslee and Tim Ryan are also paying their interns a $15 minimum wage, Huffington Post reported.

And Warren plans to do so when her internship program is launched.

Many liberals see paid internships as a necessary means to give disadvantaged students a chance to gain entry into the professional world, arguing minorities are especially limited but their inability to pay their own way.