Vice President Mike Pence has hired an outside lawyer to represent him during the Russia investigation, a sign that key members of the administration are gearing up for a protracted legal tug-of-war with Congress and Special Counsel Robert Mueller.

According to The Washington Post, Pence tapped prominent Virginia attorney Richard Cullen to serve as his outside counsel in the ongoing congressional and criminal probes. Cullen comes with a strong background in criminal-justice matters: He previously served as the state’s attorney general and as the chief federal prosecutor in its prestigious Eastern District in the 1990s before returning to private practice. The Post said Pence spent “several weeks” interviewing potential candidates, suggesting he began the process shortly after Trump ousted former FBI Director James Comey on May 9.

There have been no indications that Pence himself is a subject of or person of interest in any aspect of the sprawling Russia investigation, including questions of whether Trump committed obstruction of justice. But his possible presence at the White House during key moments to date could make him a potential witness as federal investigators delve into Trump’s treatment of the inquiry. Mueller could interview the vice president about what he saw before and after the firings of both former National-Security Adviser Michael Flynn in February and Comey in May, for example.