The phrase "a formidable obstacle for" is correct and usable in written English.
It can be used to describe a significant challenge or barrier that someone or something faces in achieving a goal or completing a task.
Example: "The lack of funding has become a formidable obstacle for the project's success."
Alternatives: "a significant barrier to" or "a major hindrance for".
That's a formidable obstacle for a critic.
Anti-forensic tools, techniques and methods are becoming a formidable obstacle for the digital forensic community.
The creek, which was a formidable obstacle for either side to pass on our left, became a very slight obstacle on our right.
It's the worst gringo hypocrisy!" Hypocrisy or not, Colombia's negative reputation can pose a formidable obstacle for locals attempting to lure American friends to visit.
A central midfield built around the muscular Patrick Vieira, Gilberto and Edu – all athletes over six feet tall who were as comfortable protecting the back four as projecting the game forwards – was a formidable obstacle for any team trying to make inroads of their own.
As yet public opposition to GMOs, especially in Europe, might still be a formidable obstacle for such relaxation.
Climate change may affect the barn swallow; drought causes weight loss and slow feather regrowth, and the expansion of the Sahara will make it a more formidable obstacle for migrating European birds.
In Mainland China, "HuKou", something like internal passport, is an unavoidable formidable obstacle for those migrant workers and their children, without which people cannot enjoy the local public resources, including elementary education.
However, the computational cost of phylogeny reconstruction (MCMC-sampling in this case) is a formidable obstacle towards using phylogeny dependent methods for identifying reassortments from very large data sets.
The war was, for a time, a formidable obstacle to any deepening of fellow feeling between Buckley and Mailer.
