The phrase "persist that" is a correct and usable phrase in written English.
It is used to express that something is firmly believed, argued, or maintained. For example, "He persisted that he was innocent."
Therefore, many uncertainties persist, that call for further research.
If tensions between Japan and China persist, that will hurt trade between the world's second- and third-largest economies, too.
Rumours persist that vote-buying is widespread.
But criticisms persist that he is too liberal for Alabama.
Although unofficial, rumors persist that Henry Cavill might follow suit.
Fallacious arguments persist that drilled solids are beneficial.
Impressions also persist that manufacturing is a man's job.
And yet, reports persist that the coach has lost the favour of his players.
Rumours persist that Flappy Bird's removal was forced, although Nguyen denies legal pressure.
Rumors persist that he sometimes gets lost while driving home, deep in thought.
Rumours persist that Duchovny and Anderson have, at one point, been involved in a sexual relationship.
