I enjoy catching idiot-in-chief's slips as much as anyone, but this
one isn't really fair. This is one of those tricky usage areas
where there is no alternative that isn't either technically incorrect
or awkward. "Corps" is technically singular, so in American usage
we want a singular verb. "Corps, which is" is probably the most
correct, but "which" sounds odd referring to persons, so Bush's "corps,
who is," seems to be a good alternative, but sounds slightly
nonsensical.
Our British brethren attack the problem at its source, permitting a
plural verb when the subject is a singular noun that refers to a
group. They would say, "the diplomatic corps, who are here,"
which sounds very odd to American ears. I suspect the American
insistence on singular agreement is a recent affectation dating from
19th-century grammar texts.
