Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
of a
occurs more and more frequently in Nonstandard Common and Vulgar English in uses such as It’s not that big of a deal; She didn’t give too long of a talk; How hard of a job do you think it’ll be? All these are analogous to How much of a job will it be?, which is clearly idiomatic and Standard, at least in the spoken language where it most frequently occurs. It is possible, therefore, that the first three could achieve idiomatic status too before long, despite the objections of many commentators. Until they do, keep them all out of your Planned and Oratorical speech and your Edited English.
When of is omitted in constructions such as a couple pair of shoes, instead of a couple of pair[s] of shoes, the usage is considered dialectal and Nonstandard, although Standard speakers from some dialect areas may use it at Casual and Intimate levels.
