"The vice president is focused entirely on his duties and promoting the President's agenda and looks forward to a swift conclusion of this matter".
Aides said the vice president had considered several candidates before settling on Cullen and made his final decision earlier this week.
Cullen served as a US attorney under President George H.W. Bush and is now the chairman of the McGuireWoods LLP law firm in Richmond, Virginia, according to ABC News.
On Wednesday, the Washington Post reported that Mueller is investigating Trump for possible obstruction of justice in the Russian Federation investigation.
The visits from both Trump and Pence are expected to have a major impact for those traveling in Miami-Dade County, as major roadways will be closed when both arrive and transit service on both Metrorail and the Metromover could be stopped for as long as 30 minutes at a time.
Vice President Pence has lawyered up. Paul Trible during the Iran-Contra investigation and was a member of former President George W. Bush's legal team during the 2000 Florida recount, according to his official biography.
President Trump has his own private lawyer, Marc Kasowitz. He has represented Trump for years in civil matters, including a libel suit against a Trump biographer that was dismissed.
Vice President Mike Pence acknowledged Thursday the "seriously wounded" Rep. Steve Scalise and the "courageous" Capitol Police officers who engaged a gunman during the congressional baseball practice shooting - saying that America will show how it pulls together at Thursday's game.