establish as

establish (oneself, someone, or something) as (something)

To confirm oneself, someone, or something's role or reputation as being a certain thing or having a certain status. That merger established the company as the biggest on the East Coast. I think you need to establish yourself as a tough teacher early on so that the kids actually listen to you.
See also: establish
Farlex Dictionary of Idioms.

establish someone or something as someone or something

to validate or confirm someone or something as someone or something. As soon as we establish her as a viable candidate, we will launch the publicity campaign. She established herself as an authority on rare books.
See also: establish
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • establish
  • establish (oneself, someone, or something) as (something)
  • certain
  • treat (someone or something) like (someone or something else)
  • treat like
  • a dead cert
  • cert
  • (somewhere or something) or bust
  • or bust
  • be a dead cert
References in classic literature
Though the company, by treaty, have a right to a participation only, in the trade of these regions, and are, in fact, but tenants on sufferance; yet have they quietly availed themselves of the original oversight, and subsequent supineness of the American government, to establish a monopoly of the trade of the river and its dependencies; and are adroitly proceeding to fortify themselves in their usurpation, by securing all the strong points of the country.
Adventures of Captain Bonneville USA in the Rocky Mountains and
[1264a] would establish a government upon a community of goods, ought to know that he should consult the experience of many years, which would plainly enough inform him whether such a scheme is useful; for almost all things have already been found out, but some have been neglected, and others which have been known have not been put in practice.
A Treatise on Government