Washington (CNN) Vice President Mike Pence has hired his own lawyer to represent him in the special counsel investigation and congressional inquiries into Russia's role in the 2016 election.

The lawyer, Richard Cullen, is a former Virginia attorney general and a former US attorney for the eastern district of Virginia. Pence interviewed several lawyers before selecting Cullen, who is based in Richmond.

The decision to hire Cullen has been in the works for weeks, aides to the vice president said. It follows President Donald Trump's decision to assemble a team of outside lawyers to represent him through the Justice Department special counsel's investigation of Russian meddling in the 2016 election.

"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," Jarrod Agen, the vice president's communications director, said Thursday night in a statement.

Cullen, reached by CNN's Kevin Bohn, Cullen said he had nothing to add beyond the official statement.

The vice president made the final decision to hire Cullen earlier this week, an aide told CNN, and stressed that the decision to hire Cullen was not prompted by anything.

Russia investigation

Pence's hire comes just one day after The Washington Post reported Justice Department special counsel Robert Mueller is investigating Trump for obstruction of justice. Mueller is reportedly interviewing three top intelligence officials -- Director of National Intelligence Dan Coats, National Security Agency Director Mike Rogers and retired deputy NSA director Richard Ledgett -- as part of the probe, as early as this week.

In a tweet Thursday morning, Trump called the Post's report "phony."

"They made up a phony collusion with the Russians story, found zero proof, so now they go for obstruction of justice on the phony story," he wrote. "Nice."

They made up a phony collusion with the Russians story, found zero proof, so now they go for obstruction of justice on the phony story. Nice — Donald J. Trump (@realDonaldTrump) June 15, 2017

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 Russia.

"As has been stated repeatedly and the President has been told, he's not under investigation," Pence told reporters on Capitol Hill in May. "There is no evidence of collusion between our campaign and any Russian officials."

A senior administration adviser acknowledged there have been weeks of hand-wringing behind closed doors among members of Pence's team, and an acceptance that the questions about Russia and the Trump campaign were not disappearing. Pence has been under fire for not knowing a number of things that happened during the transition -- which he led as chairman.

A number of Pence advisers and staff worked out of Trump Tower during the transition -- and are now worried about being dragged into legal issues.

A senior administration adviser explained the nervousness: "You just worry about some meeting or call that you were at and don't recall even innocuous in nature, and then you get pounced on." The adviser said that people on Pence's staff have not lawyered up as far as this person knew but added, "man, what a stressful deal."

The adviser offered CNN a different version of why Pence was out of the loop during the transition: he was concerned with Senate confirmable personnel.

"The primary focus for Pence was Cabinet level, as the President had selected his senior staff," this person said.

How he'll pay

So how is the vice president going to pay for his new personal lawyer?

A Pence adviser told CNN the legal fees will be paid through "non-taxpayer funds." The adviser declined to elaborate whether it would come out of Pence's pocket -- doubtful, given his modest net worth -- or a campaign fund of some kind.

The vice president recently opened a leadership PAC, the Great American Committee. He is having a fundraising event Friday night in Indianapolis.

That may be one option. But the fees could also be paid through other avenues, ranging from the Trump-Pence re-election committee or some type of Republican National Committee fund.

Two Washington campaign finance lawyers said Thursday night the rules offer leeway when hiring outside legal representation.

Bob Bauer, a Democratic lawyer whose practice includes advising clients on campaign finance issues, told CNN it would raise concerns if Pence used his leadership PAC to pay his legal fees.

"It is a problem if a committee is formed and money raised for the expressed purpose of supporting candidates and normal political activities," Bauer said, "but the intention is in fact to establish a personal legal expense fund."