Virginia Rep. Don Beyer went on an extensive tweetstorm late Thursday, accusing President Donald Trump and billionaire investor Carl Icahn of “profiting off of the public trust and taxpayer dollars” and denouncing the lack of White House oversight.

In a series of 38 Twitter posts, Beyer, a Democrat, summarized a report published last week by the New Yorker, which detailed the close ties between Trump and Icahn, and the potential conflicts of interest and possible illegality of some of Icahn’s actions while he served as a special adviser to the president.

“ “Trump and his cronies, including one of the richest people on the planet, are profiting off of the public trust and taxpayer dollars. . . . It’s deeply wrong.” ” — Rep. Don Beyer

The report found Icahn benefited tremendously earlier this year from price changes of ethanol credits for owners of oil refineries.

The controversy centers around federal regulations for oil refiners. Companies are required to either blend ethanol into their gasoline or buy renewable-fuel credits, known as “Renewable Identification Numbers,” from refiners that do. When Icahn bought a controlling stake in CVR Energy in 2012, the price of RINS credits was about 5 cents each. But the price soared in later years, to the point that the company was spending $200 million a year on RINS by 2016, and had seen its stock value fall 70%.

Icahn had unsuccessfully lobbied the Obama administration to change the rules, and as Trump’s special adviser urged the same. The price of RINS dropped after Icahn joined Trump’s team last December, and fell even more in February, after Icahn reached a deal with the Renewable Fuels Association, an ethanol industry advocacy group, to reverse its policy and support changes to the ethanol blending requirement. Prices of the credits dropped yet again when word of an executive order on ethanol blending was leaked.

In the months after Icahn joined Trump’s team, CVR Energy stock soared, helped by the reduced cost that RINS credits were taking on its bottom line. The New Yorker found Icahn personally reaped half a billion dollars, on paper at least. Meanwhile, CVR had been shorting RINS, selling them at a higher cost in anticipation of their price soon falling, according to a Reuters report in May, a gamble one analyst termed at the time “impossible.”

The New Yorker report suggested Icahn may have used his position as White House adviser to influence the price of RINS credits and exposed himself to potential insider-trading violations.

“This Congress is not doing its job,” Beyer said in one of his tweets Thursday. “It is allowing norms to be violated, influence to be peddled, corruption to fester. It’s horrible. . . . This matters more than party. Congress must provide oversight and prevent anything like this, like Carl Icahn, from happening again.”

Icahn’s attorney told the New Yorker that Icahn did not exploit his relationship with Trump to profit from RINS short-sales, and that conflict-of-interest laws would not apply to Icahn because he was serving in an unofficial, unpaid role.

Icahn stepped down from his post as Trump’s adviser last Friday, the same day the New Yorker article was published online, saying he didn’t want “partisan bickering about my role” to cloud the administration.

In the past year, CVR stock has gained nearly 36%, although it has started falling back to Earth of late. After peaking at $26.91 in January, CVR CVI, +3.29% ended Thursday at $18.86 a share, down almost 26% year to date, compared to the S&P 500’s SPX, +0.12% 9% gain this year, and 12% gain from a year ago.

Here’s Beyer’s initial Twitter post (click it to see his entire thread):