Speaking at the inaugural Conference on Prosperity and Security in Central America today, Vice President Mike Pence announced he will travel to Central and South America in August on behalf of President Trump.
Pence spokesman Jarrod Agen confirmed the hire and said the Vice President wants a "swift" resolution. Cullen referred questions to the vice president's office. Michael Flynn, Trump's former national security adviser, misled Pence about his contacts with Russian officials - Pence then repeated the incorrect claims publicly.
US intelligence agencies have concluded that Moscow interfered in last year's presidential campaign to try to tilt the vote in Trump's favor.
An aide tells NPR the decision to hire an outside lawyer has been under consideration for weeks, and Pence chose to go forward with it earlier this week. He also said the US wants to secure its borders to "bolster USA national security" as part of the agenda of President Donald Trump.
Cullen's hiring was first reported by the Washington Post.
The new allegations against Trump centre on his own admission that he fired Comey because of the Russian Federation investigation, and suggestions he asked several top intelligence officials for their help altering the direction of the inquiry. Just before the story broke, Trump wrote a pair of angry tweets, suggesting that Hillary Clinton, his Democratic opponent in the election, should be under investigation instead of him.Earlier on Thursday, Trump called the probe a "witch hunt" on Twitter.
While James Comey was FBI director, he told President Trump he was not personally under investigation when the president asked him, but that applied only to the period preceding his May 9 firing. "Mueller is setting up a dragnet of obstruction, financial questions and every aspect of Trump's life and his associates lives", said former House Speaker Newt Gingrich, who labeled it "very unsafe".
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.