The Vatican has begun a formal investigation into the diocese of a Texas bishop who has publicly accused Pope Francis of effectively undermining the Roman Catholic faith.

Bishop Joseph Strickland, who presides over the Diocese of Tyler, Texas, and has described himself as a "red-pilled bishop," was recently subject to a days-long "apostolic visitation" from Rome, according National Catholic Reporter (NCR).

Elizabeth Slaten, the communications director for the diocese, confirmed to NCR on Monday that the visitation took place last week, though she did not offer further information to the outlet regarding who was involved with it.

"The whole process was very confidential," Slaten told the outlet. "The whole thing was conducted by the Holy See. We respect their processes. I'm not free to speak on behalf of Mother Church and the nuncio."

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Photo of Bishop Joseph Strickland

Bishop Joseph Strickland, who presides over the Diocese of Tyler, Texas, and has described himself as a "red-pilled bishop," was recently subject to a days-long "apostolic visitation" from Rome. (Screenshot/YouTube)

Strickland was appointed to his position by Pope Benedict XVI in 2012 and has since made headlines for his willingness to publicly criticize the leadership of the Church, including the pope.

Strickland seemingly called the pope's fidelity to the faith into question in a May 12 tweet, writing, "I believe Pope Francis is the Pope but it is time for me to say that I reject his program of undermining the Deposit of Faith. Follow Jesus."

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Pope Francis is seen in Vatican City

Bishop Joseph Strickland challenged Pope Francis to fire him in 2020 and has publicly claimed the Roman Catholic Church has become "weak" under his leadership. (Stefano Costantino/SOPA Images/LightRocket via Getty Images)

In 2020, Strickland maintained that the Roman Catholic Church has become "weak" under the leadership of the current pontiff and challenged Francis to fire him. He has also retweeted a video blasting Pope Francis as a "diabolically disoriented clown," NCR noted.

The bishop has also been outspoken in his criticism of U.S. political leaders such as President Biden, whom he has regularly admonished for straying from Catholic teaching such as supporting taxpayer-funded abortion. In March, he criticized Biden's administration and warned the government is sliding "closer to collapse."

President Joe Biden

Bishop Joseph Strickland has rebuked President Biden for straying from Catholic teachings on issues such as abortion. (SAUL LOEB/AFP via Getty Images)

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Fox News Digital has reached out to the Vatican Embassy in Washington, D.C., for comment. Strickland declined request for comment.

Fox News Digital's Timothy H.J. Nerozzi contributed to this report.