"primary allegation" is correct and usable in written English.
It could be used in any sentence where you are discussing a main claim. For example, "The primary allegation in the case was that the defendant had committed fraud."
The primary allegation the commission is investigating is that Microsoft designed its Windows 2000 software to function best with its own servers, squeezing out rivals.
The commission's primary allegation is that Microsoft designed Windows 2000 to function better with the company's own servers in order to squeeze out rivals and that the firm is withholding vital information to prevent competitors remedying the situation.
All we knew was that BART had received 66 complaints, with excessive use of force being the primary allegation, according to a 2010 audit.
The CFTCs primary allegation is that BPs rampant buying raised the price of propane, hurting homeowners across the Northeast trying to heat their homes in February.
In 1997, failure of communication was the fourth most common primary allegation in malpractice suits against US radiologists; 60% of these claims resulted from failure to emphasise an urgent or unexpected abnormal finding [35].
The Trust had approximately 20,000 acres (8,165 hectares) of timberland in Monroe and Conecuh counties in the southern part of the state, and the primary allegation was that the trustee had failed to buy casualty-loss insurance for the standing timber on it.
In fact, his most recent ad suggests that he's the next presidential comeback kid, a term coined by Bill Clinton in 1992, after coming in a surprisingly strong second in the New Hampshire primary after allegations surfaced of an extramarital affair.
He was the primary source of allegations that led to the company being described as "evil" by Margaret Hodge, the chair of the public accounts committee, and to being accused of misleading the committee – a claim Google denied.
Ms. Haley, 38, upended things again last week after a sharp-elbowed primary that included allegations of marital infidelity and pitted her against the lieutenant governor, the attorney general and a congressman.
Weeks after losing their primary winner, Jack Ryan, over allegations stemming from his divorce, the Republicans have finally settled on Plan B: Mr. Keyes, a hard-core conservative who has carved out a career as a sort of professional unsuccessful candidate.
But over the weekend, it was Democrats who displayed that type of chaos at the Nevada state convention, in an episode illustrates the current state of the Democratic primary — one mired by allegations, mostly from Bernie Sanders supporters, of misdeeds and dirty tricks.
