The phrase "a main partner" is correct and usable in written English.
It can be used to refer to a primary or significant partner in a business, project, or relationship context.
Example: "In our new venture, we are excited to collaborate with a main partner who shares our vision for sustainability."
Alternatives: "a primary partner" or "a key partner".
Jimmy Ryan, Citi's top Democratic lobbyist, left Citi in early 2009 to become a main partner at a lobbying firm started by Steven Elmendorf, a veteran Democratic hand.
In 2005, it launched its first commercial satellite on a Russian rocket in a project with Moscow, a main partner in transferring space technology to Iran.
Mr. Mohammed, the American-educated Kuwaiti from Pakistan who emerges in the commission's account as a main partner of Mr. bin Laden, at one point planned an attack involving 10 planes.
We were worried that instability in France and Germany might cause the community to disintegrate; we were also concerned that if the community prospered and achieved the promised cohesion it would become something from which we would not want to be excluded, particularly as the United States would be inclined to regard it as a main partner in Europe.
Great news this month, with the announcement of Jaguar as a main partner in our World Land Speed Record attempt.
German luxury watch brand Glashütte Original has been a main partner to the Berlin Film Festival (Berlinale) for the past five years.
He says that it's growing so fast right now that it might be the next IPO target, although given that it's also a main partner of Baidu, things could go in another direction.
We found that perceived condom use and a main partners refusal to use condoms when asked were important determinants of reported condom use with main partners among sex workers in Madagascar.
Sexual behaviour questions enquired about whether participants had a main sexual partner, other sexual partners, ever had sex, ever had STI, and ever tested for HIV using a scale from 0 to 1 (0 = No, 1 = Yes).
Three relationship-level characteristics were obtained in reference to an individual's main partner.
More than 40% of participants reported never using a condom with their main partner, compared to 0.5% who never used male condoms with clients.
