Q: Given a sentence and two mentions from the text (arguments), indicate a phrase (a verb or noun phrase) that describes the relationship between the provided arguments.
Sentence: 'Over at SCOTUSblog , Tom Goldstein has a long post on who a Democratic president might nominate to fill the Supreme Court vacancies that would surely open up if the GOP exits the White House in 2008 .', Argument/Subject 1: 'vacancy', Argument/Subject 2: 'president'
A:
be fill by