The phrase "a leading proposal" is correct and usable in written English.
It can be used when referring to a proposal that is considered to be at the forefront or most influential in a particular context or discussion.
Example: "After reviewing all submissions, we have decided to move forward with a leading proposal that addresses our key objectives."
Alternatives: "a primary proposal" or "a prominent proposal".
A leading proposal to rescue Lehman would have divided the bank into two entities, a "good bank" and a "bad bank".
Three officials involved in the discussions said that a leading proposal was to send a battalion-sized group  about 800 troops.
A leading proposal is that the bobsleigh and luge track be taken over by the state, while the remaining venues be retained by the company and jointly funded by the municipality and Oppland County Municipality.
You can see that truth in financial reform and even in in the debate over health care: The Progressive States Network has organized a letter to Congress signed by more than 1,000 state legislators demanding real reform, and a leading proposal before Congress would allow states to administer their own public plan options.
Under a leading proposal, the federal Office of Personnel Management would negotiate with insurers to offer one or more national health plans to individuals, families and small businesses.
The leading proposal in Pennsylvania would give the tracks a 49% cut, and a slots plan to be voted on in Bangor, Me., would let the track owner keep roughly 60%, says a city official.
Marianna Coval, executive director of the Brooklyn Bridge Park Coalition, said the leading proposal was to convert the building into a walled garden and cafe.
But several people with knowledge of the discussions said there was no leading proposal as of Thursday night.
The leading proposal, offered by Senator Bob Graham, Democrat of Florida, would provide drug coverage as a standard part of the Medicare benefit package.
Cutting corporate income tax rates has become the administration's leading proposal, and it is also being pushed heavily by large businesses.
