The phrase "a core message of" is correct and usable in written English.
It can be used when discussing the main idea or central theme of a text, speech, or piece of communication.
Example: "The author emphasizes a core message of resilience throughout the novel, encouraging readers to persevere in the face of adversity."
Alternatives: "a central theme of" or "a fundamental idea of".
Populist progressives like Senators Bernie Sanders and Elizabeth Warren have made combating the influence of money in politics a core message of their presidential candidacies — arguments that might have proved challenging for Mr. Bloomberg, whose aides said he would spend at least $500 million of his own fortune to defeat President Trump in 2020.
That's a core message of Juggling Work and Caregiving, a free new e-book from AARP aging and families expert Amy Goyer.
This is a core message of Kymlicka's essay with which I agree entirely: in order to win democratic support for their agenda, progressives must be able to convince citizens that their immigration and multicultural policies do not kill their egalitarian social policies.
But, reaffirming a core message of his campaign, he insisted that such programs must simultaneously demand greater responsibility if they are to succeed.
A core message of risks from exit, so the logic ran, would drive ditherers/undecideds/don't knows, who tend to be risk averse, towards Remain.
The deeper problem, counterintuitive though it may seem, is that the more we focus on test scores -- and focusing on test scores is a core message of Rhee's particular brand of advocacy -- the less likely we are to improve the quality of our public schools.
Certainly sometimes it's an important message that I do need to read, but most of the time it's just a core message filled with paragraphs of bloat.
A further core message of this document is that in countries where prenatal screening is offered as a public health programme, governments and public health authorities should adopt an active role to ensure the responsible innovation of prenatal screening on the basis of ethical principles.
Annual repetition of a core message lands this thought with the consumer, and the brand still has the opportunity to keep the creative fresh each year with a reinterpretation of the central theme".
Visit Jay Baer's website, for instance, and you'll notice one thing right away: it's called "Convince & Convert". Jay's philosophy is to help businesses use social media to persuade their audience of a core message, and with clients like Wal-Mart and Petco under his belt, it's clearly working.
Its weaknesses are less a question of leadership (though anybody else wanting to challenge Nick Clegg or Chris Huhne next time around had better get their skates on) than of communicating a core message and deciding on a political strategy.
