Hillary Clinton is interviewed by Mariella Frostrup (not pictured) at the Cheltenham Literature Festival on October 15, 2017 in Cheltenham, England.

Criticism is flying from both sides of the U.S. political aisle after a new book from a former party insider suggested that Hillary Clinton had been controlling elements of the Democratic National Committee since long before she became the party's nominee.

In the book, an excerpt of which was published Thursday by Politico, former DNC interim chair Donna Brazile describes how she discovered an arrangement between Clinton's camp and the party's main apparatus that she found ethically dubious.

That is, Brazile wrote that the former secretary of state's campaign had entered into an agreement with the DNC whereby she would help the party with money in exchange for having a say over key decisions. That's raising eyebrows because Clinton hadn't yet wrapped up the nomination against Sen. Bernie Sanders when she was exerting influence over the DNC.

The arrangement with Clinton's campaign, Brazile said, "was not illegal, but it sure looked unethical. If the fight had been fair, one campaign would not have control of the party before the voters had decided which one they wanted to lead. This was not a criminal act, but as I saw it, it compromised the party's integrity."

Multiple organizations reported Friday on a 2015 document outlining a formal agreement by which Clinton's campaign would help the DNC with money in exchange for a certain say in how the organization was run. Here are the terms of the deal, according to a memorandum obtained by NBC News between former DNC CEO Amy Dacey and Robby Mook, who was the campaign manager of Hillary For America (HFA, the official name for Clinton's campaign):

1. With respect to the hiring of a DNC Communications Director, the DNC agrees that no later than September 11, 2015 it will hire one of two candidates previously identified as acceptable to HFA. 2. With respect to the hiring of future DNC senior staff in the communications, technology, and research departments, in the case of vacancy, the DNC will maintain the authority to make the final decision as between candidates acceptable to HFA. 3. Agreement by the DNC that HFA personnel will be consulted and have joint authority over strategic decisions over the staffing, budget, expenditures, and general election related communications, data, technology, analytics, and research. The DNC will provide HFA advance opportunity to review on-line or mass email, communications that features a particular Democratic primary candidate. This does not include any communications related to primary debates – which will be exclusively controlled by the DNC. The DNC will alert HFA in advance of mailing any direct mail communications that features a particular Democratic primary candidate or his or her signature. 4. If asked by a State Party, the DNC will encourage the State Party to become a participant in the Victory Fund.

At least in writing, the deal between Clinton's camp and the Democratic group sought to avoid impropriety.

According to the document obtained by NBC, the agreement was explicit that it should not "be construed to violate the DNC's obligation of impartiality and neutrality through the Nominating process." Furthermore, the memorandum says that the Clinton campaign's input into the party "will be focused exclusively on preparations for the General Election and not the Democratic Primary."

Yet despite those written assurances, the condemnation has been quick. Democratic Sen. Elizabeth Warren said in response to the Brazile revelations that she thought the primary process had essentially been rigged in favor of Clinton.

Others from the left also condemned the arrangement as evidence the cards were stacked against Sanders, revealing that the intra-party wounds from the election had not fulled healed.

Although the DNC cannot affect the primary vote tallies, many Sanders supporters have pointed out that the party organization scheduled debates on weekend nights. Fewer people would be watching at that time, so fewer people could change their minds in favor of the trailing Sanders, the frequent complaint alleged.

Unsurprisingly, President Donald Trump latched onto Brazile's and Warren's comments to take another swing at the woman he defeated in the general election, writing that the "New Donna B book says she paid for and stole the Dem Primary."

"The real story on Collusion [sic] is in Donna B's new book. Crooked Hillary bought the DNC & then stole the Democratic Primary from Crazy Bernie!" Trump said in another Twitter post.

"Pocahontas just stated that the Democrats, lead [sic] by the legendary Crooked Hillary Clinton, rigged the Primaries! Lets [sic] go FBI & Justice Dept," the president added in a subsequent post, reusing a name with which he's taunted Warren because of her claims of Native American heritage. Many consider that term an ethnic slur.

Trump tweet: The real story on Collusion is in Donna B's new book. Crooked Hillary bought the DNC & then stole the Democratic Primary from Crazy Bernie!

Trump tweet: Pocahontas just stated that the Democrats, lead by the legendary Crooked Hillary Clinton, rigged the Primaries! Lets go FBI & Justice Dept.

It's not clear what oversight, if any, the Department of Justice or FBI would have over the DNC's internal dealings as it is not a government organization. There are currently multiple investigations of the Trump administration and campaign, but they are looking not at internal Republican matters, but rather its alleged collusion with a foreign government in Moscow.