The phrase "a core issue of" is correct and usable in written English.
It can be used to highlight a fundamental or central problem related to a particular topic or situation.
Example: "The report identifies a core issue of communication breakdown within the team that needs to be addressed."
Alternatives: "a fundamental problem of" or "a central concern of".
"It is a core issue of free speech," Mr. Guzofsky said.
Her peers and rivals of the center-left criticized her for abandoning a core issue of the left: peace.
"The issue of women and girls, and body issues and self-esteem, is a core issue of mine," she told the Guardian.
The president's account yesterday of the CIA interrogation and detention of Mohammed and other suspects also appeared designed to enshrine national security as a core issue of November's congressional elections.
Ban, who will step down at the end of the year after a decade in charge of the United Nations, has made action on climate change a core issue of his time in office.
All democrats should, of course, but during the authoritarian age of Tony Blair and Michael Howard, civil liberties became a core issue of identity and recognition – what Lib Dems were for.
On migration – a core issue in many of Labour's heartlands – Smith said it was something "we need to be proud of" and that it was vital for services such as the NHS, highlighting the international nature of his own family.
The fate of the site is a core issue at the heart of the conflict between Israel and the Palestinians.
The cost of drugs has been a core issue from the time of the first DTCs.
The 77-page opinion surveyed the history of the prosecution and highlighted a core issue at the heart of the government's case: Was the transaction in question merely an aggressive accounting technique or something more sinister?
The relationship between these two elements – and the role of the environment in mediating them – is a core issue in the conceptualization of, and social response to, disability.
