The phrase "asserting it with" is correct and usable in written English.
You can use it when you want to indicate that someone is making a claim or statement in a particular manner or with a specific emphasis.
Example: "She was asserting it with such confidence that everyone believed her."
Alternatives: "stating it with" or "declaring it with".
You have to credit the south-west; it has done quite the PR job on clotted cream, asserting it (with its PDO status) as the natural choice in a cream tea, despite it having nothing to recommend it.
She imbued that truth so deeply that nigh on seven generations of denial later, her descendants were still asserting it with such fierce determination that history was finally set straight.
But the reader should note that the crucial claims are that someone who asserts (2) is either asserting it with a meaning other than the standard conventional one, or with no meaning at all.
Shakespeare seems to be asserting it is, but with modern eyes wary of his treatment of Shylock, we wonder.
Defense lawyers have attacked the lead F.B.I. special agent in the case, Stanley Ornellas, and an affidavit he filed to get a search warrant for Mr. Pellicano's offices, asserting it was rife with misrepresentations and omissions.
By means of answering the question what I believe with an utterance of (22) I do represent myself as believing that there are black swans, equivalently with asserting it.
It may be asked whether a statement of the world's unity is a precondition for asserting its identity with God, or a consequence of asserting it?
European Union countries say they lose billions in revenue as a result of tax evasion, with Germany asserting it is deprived of as much as 30 billion euros ($45.6 billion) a year.
It has not only been the rival videos that have been struggling for attention but associated hashtags too, often mirroring each others' messages: Hamas asserting it is "ready to rule" with Fatah saying it is "able to rule".
"Even if that gets dropped out, the Federal Reserve as the regulator bothers people," he said, noting some of its critics assert it is too cozy with the financial institutions it regulates.
Rather, he asserted it was packaged with a passion that might as well define him.
