Pence's spokesman says he's hired an outside counsel to help him deal with inquiries related to the probe.
Cullen also served as the attorney general of Virginia and as a USA attorney under President George H.W. Bush. He's had experience in dealing with Washington investigations from Watergate to the Iran-Contra affair, according to his biography on the firm's website.
At a conference on Central American security and economic issues, officials in the administration of President Donald Trump made the point repeatedly that strengthening the US border and reducing the flow of migrants- key elements of Trump's agenda - depend on stabilizing the region, which has been engulfed in drug-fueled violence in recent years.
Pence, who after the election served as head of Trump's White House transition team, has stood by Trump's assertion that there are no ties between Trump's campaign and Russian Federation.
Cullen is a former federal prosecutor who has long ties to former FBI Director James Comey, whom Trump fired on May 9.
G7 summit kicks off in Italy
The group says that it represents 120 million Americans and $6.2 trillion in contributions to the US economy. The United States' current relations with our allies in Europe will be damaged further due to this move.
U.S. Secretary of State Rex Tillerson is meeting with leaders of Central America and senior officials from Mexico as President Donald Trump signals a policy shift toward the region.
President Donald Trump responded angrily to reports he is under criminal investigation Thursday, deriding a "witch hunt" against him led by some "very bad" people.
An examination of possible obstruction of justice charges was "unavoidable" given testimony by Comey, although the issue may not become the main focus of the probe, the source said.
Pence's announcement comes after several weeks of deliberations, featuring several candidates, an administration official said, adding that no taxpayer money will be used.
Examining the possibility of obstruction charges will allow investigators to interview key administration figures including Attorney General Jeff Sessions, Deputy Attorney General Rod Rosenstein and possibly Trump himself, said the source familiar with the Mueller investigation. Trump has already hired his own outside lawyer.
Trump did not directly address the allegations that he is being probed for possibly obstructing justice, a potentially impeachable offense.