Stressing transparency in government, more than a half-dozen Democrats running for the White House have released their tax returns.

And while the filings are a way for the Democratic candidates to spotlight Republican President Trump’s refusal to release his taxes -- both as a 2016 White House candidate and as a sitting president -- the returns also have revealed that some of the biggest class warriors of the 2020 field happen to be among the wealthiest.

AT FOX NEWS TOWN HALL, BERNIE SANDERS MAKES NO APOLOGIES FOR HIS WEALTH

"This year, we had $560,000 in income," Sen. Bernie Sanders of Vermont explained Monday night during a Fox News town hall.

Minutes before the start of the town hall in Bethlehem, Pennsylvania, the independent senator from Vermont’s presidential campaign released his 2018 returns. According to the figures, Sanders and his wife Jane paid a 26 percent effective tax rate on $561,293 in income, and made more than $1 million in both 2016 and 2017. Nearly $400,000 of his income last year came from book sales.

Sanders doubled down on his previous defenses of his wealth, which even some progressives have criticized considering his advocacy for an increase in the tax rates the wealthiest Americans pay.

2020 CANDIDATES' TAX RETURNS: BY THE NUMBERS

"In my and my wife's case, I wrote a pretty good book. It was a bestseller, sold all over the world, and we made money. If anyone thinks I should apologize for writing a bestselling book, I'm sorry, I'm not gonna do it," he said.

And Sanders, who’s faced calls for the past month to release his returns, acknowledged that he had been "fortunate" even as he pushed for a more progressive tax system.

WARREN RELEASES RETURNS MOMENTS AFTER PUSHING WEALTH TAX

Sanders isn’t the only populist senator running for the White House whose tax returns indicate income in the upper six-digits.

Minutes after pushing her proposal to increase taxes on the ultra-wealthy, Sen. Elizabeth Warren released her tax returns last week. The figures show that the Massachusetts Democrat and her husband Bruce – a professor at Harvard University – paid more than $230,000 in taxes last year on just over $846,000 in adjusted income, for an effective tax rate of 27 percent. Warren made about $325,000 in book sales in addition to the $175,000 salary she receives as a senator. Her husband earned around $400,000 from Harvard.

The wealthiest Democrat among those 2020 candidates who’ve so far made their tax returns public is Sen. Kamala Harris of California.

The former Golden State attorney general and her husband – attorney Doug Emhoff – reported an adjusted income of nearly $1.9 million in 2018. They paid nearly $700,000 in taxes, for an effective rate of 37 percent. Besides her Senate income, Harris earned around $320,000 in income from writing a book that was published earlier this year. Her husband earned $1.5 million for his work as an attorney.

While Harris is reporting the most income of the candidates who’ve so far released their 2018 tax returns, former Rep. John Delaney of Maryland appears to be the wealthiest candidate in the field of Democratic presidential nomination contenders.

Last year, the then-three-term congressman was listed as the sixth wealthiest member of Congress, with an estimated net worth of $92.6 million according to rankings from Roll Call. Delaney, who grew up in a working-class family in New Jersey, became the youngest CEO in the history of the New York Stock Exchange.

According to his first quarter of fundraising report, the candidate infused $11.7 million of his own money into his campaign, making up the vast majority of the $12.1 million he brought in during the first three months of the year.

Former Rep. Beto O’Rourke and his wife, meanwhile, made $366,455 – according to their 2017 returns – paying an effective tax rate of 22 percent. The candidate released 10 years of returns on Monday, but didn’t include his 2018 taxes.

"As a candidate aspiring to restore the American people's trust in the nation's highest office, O'Rourke will also release his 2018 tax returns as soon as possible after they are filed," his campaign explained.

Sen. Amy Klobuchar of Minnesota and her husband earned $338,121 last year, paying a 19 percent effective tax rate. Sen. Kirsten Gillibrand and her husband earned nearly $215,000 in income last year, paying an effective tax rate of 14 percent.

GILLIBRAND THE FIRST 2020 DEMOCRAT TO RELEASE TAX RETURNS

Gillibrand became the first of the 2020 Democrats to make public her returns, when she released her returns on March 27.

“Join me in calling on every presidential candidate to disclose their taxes. This is what transparency and accountability is all about,” Gillibrand said in a video at the time, as she challenged the rest of the Democratic 2020 contenders to make their returns public.

Washington State Gov. Jay Inslee also released his returns, indicating that he and his wife earned nearly $203,000 last year, paying an effective tax rate of 15 percent.