Could there be only a sole interest in their project?

One that I would take up, except for my sole interest in ranching.

My sole interest in life right now is to protect Jerry.

The critics say their sole interest in the question is to improve the voting system.

His sole interest was how much damage they could do.

The Council members are not acting in the sole interests of the city.

He saw to it that her sole interest was music.

His was far from the sole interest at stake.

But his sole interest was in leaving the world a better place than he had found it.

War, conquest, and bloodshed were their sole interests in life.