Senators pushed forward with a hearing Wednesday on whether to extend FBI Director Robert Mueller’s term by two years even as one legal expert testified that the move would be unconstitutional. 

Some of the lawmakers on the Senate Judiciary Committee expressed concern that extending Mueller’s term beyond the 10-year limit could set a dangerous precedent, though the majority of senators on the panel supported the extension, which was proposed by President Obama last month.  

“Changing the tenured term limit is a one-time situation that will not be routinely repeated,” said Sen. Chuck GrassleyCharles (Chuck) Ernest GrassleyLet Robert Mueller do his job Overnight Cybersecurity: Senators eye path forward on election security bill | Facebook isn't winning over privacy advocates | New hacks target health care Juan Williams: GOP support for Trump begins to crack MORE (Iowa), the committee's ranking Republican.  

Mueller said he didn’t immediately agree with Obama that an extension of his term was the best thing for the future of the FBI. But after much thought and advice from friends, colleagues, and his family, Mueller said he agreed to stay on if Congress votes in favor of the move. 

“Nobody is indispensable and some of the calculus was: Should I really stay?” said Mueller. 

“And often the person who is in that position is the worst person to make that decision. So I did go out and try to talk to other persons, both in the bureau and outside the bureau, to get a more objective view as to whether or not it would be the best thing for the agency for me to stay for this time, even though the president had asked that that be done.”

But University of Virginia law professor John Harrison told members of the panel that the bill put forward by committee Chairman Sen. Patrick LeahyPatrick Joseph LeahyCongress should build on the momentum from spending bill Overnight Tech: Zuckerberg grilled by lawmakers over data scandal | What we learned from marathon hearing | Facebook hit with class action lawsuit | Twitter endorses political ad disclosure bill | Uber buys bike share Overnight Cybersecurity: Zuckerberg faces grilling in marathon hearing | What we learned from Facebook chief | Dems press Ryan to help get Russia hacking records | Top Trump security adviser resigning MORE (D-Vt.) to extend Mueller’s term “would be inconsistent with the Constitution because it would seek to exercise through legislation the power to appoint an officer of the United States, a power that may be exercised only by the president, a head of department, or a court of law.”

Grassley argued that the 10-year term for Mueller’s position was key to giving the FBI director a barrier of political independence from the president and Congress. The term limit also reduces the power of the director and helps preserve civil liberties, he said. 

Mueller declined to comment on whether he thought the threats facing the country were sufficient enough to warrant him staying in his job, but he pointed to ongoing efforts to fight terrorists and cyber attacks as two key areas that he would focus on if approved for another two years.  

“The areas of concentration for the next two years should continue to be terrorism, particularly in the wake of the death of bin Laden [and] the impact that’ll have on his adherents,” said Mueller.