The phrase "a main stumbling block" is correct and usable in written English.
It can be used to refer to a significant obstacle or difficulty that hinders progress in a situation or project.
Example: "The lack of funding has become a main stumbling block in the development of the new software."
Alternatives: "a major obstacle" or "a key barrier".
With many West Coast ports shut down by a strike, is the main stumbling block over a single, low-level official who rules on disputes involving dock workers?
As Congress repeatedly tried to find a legislative solution, the main stumbling block was Mr. Bush's insistence on legal immunity for the phone companies.
The union was the last major labor group at Southwest without a new contract; the main stumbling block had been wages.
Disagreement over who might lead a new administration had been cited as the main stumbling block to an agreement, despite the threat of a Greek exit from the eurozone if Athens failed to approve a bailout accord hammered out by EU leaders last month.
It is a war between man and a bacterium and the outcome is by no means certain.Many people believe that the main stumbling block is a lack of new antibiotics.
The main stumbling block is a city zoning requirement that the building have 26 parking spaces, said Scott Domansky, a principal of PRD.
Over the past five years, 271 partners have left, including 80 in America.Clifford Chance's "lockstep" system of remuneration, espoused by most English firms, seems to have been the main stumbling block to a happier union.
Neither paper, however, mentioned the main stumbling block in a state‐city agreement: Mr. Wright works for Gov. George R. Ariyoshi, political rival of Mr. Hayashida's boss, Mayor Frank F. Fasi.
So Uzbekistan is the main stumbling block to a Central Asian union.The Uzbeks, who make up around half of Central Asia's 55m people, see themselves as the region's natural and historic leaders (though there is nothing to back up this claim today).
