"widening influence" is a correct and usable phrase in written English.
It refers to the expanding or growing effect that someone or something has on a particular situation or group of people. You can use "widening influence" in a variety of contexts, such as in discussing the impact of a leader, a business, a trend, or a policy. Here is an example: "The company's innovative marketing strategies have led to a widening influence in the industry, attracting a larger and more diverse customer base."
He noted its steady increases in drug cultivation, the widening influence of rebels and its general potential to destabilize the region, given Colombia's position between the Panama Canal and Venezuela, the largest foreign supplier of oil to the United States.
But now, the company's widening influence is coming under scrutiny by federal prosecutors, who are examining the relationship between Dandong's wealthy and connected chairman, Wang Wenliang, and Gov. Terry McAuliffe of Virginia, a Democrat who was elected in 2013.
Many of these went on to write for the newly established weekly, New Society, an intellectual home that came ready-furnished as a result of Colin's widening influence at this time.
Less impressed by her wardrobe than by her infectious mix of ebullience and propriety, Seventh Avenue designers as diverse as Vera Wang, Tory Burch, Peter Som and Tommy Hilfiger have acknowledged her widening influence.
Seeking a strategy that skirts the widening influence of Wal-Mart Stores in the grocery business, Albertsons said yesterday that it would spend $2.47 billion to buy the New England-based Shaw's chain of supermarkets from its British parent, J Sainsbury.
The abruptness of the termination, even if temporary, also suggested that the Russians, eager to show widening influence in the Middle East, had seriously misread how a public announcement of their use of the Hamadan base in western Iran would reverberate among Iranians.
It has already given Russian passports to many residents of both places, thereby widening its influence.
China can have its cake and eat it too, widening its influence while overturning nothing, something that Russia may yet figure out as well.
And with Iran now widening its influence in Syria and in Lebanon, by way of Hezbollah, Israelis may be too wary to replace Netanyahu, their self-styled Mr. Security.
There is also a sense of what some see as military melodrama – such as dropping the "Mother of All Bombs" and bombing Taliban drug labs – as substitutes for dealing with the thornier issues of official corruption and widening Taliban influence.
Mr. Casey is said to want to appoint a strong Democrat who could run for a full term as Treasurer next year, thus widening Democratic influence at the top of the state government.
