When do senators resign to assume the presidency or vice presidency?

Newsmax TV host Grant Stinchfield suggested that Vice President-elect Sen. Kamala Harris is holding onto her Senate seat because of the inaccurate claim that President Donald Trump can still win reelection.

"Harris is a woman who has yet to resign from the United States Senate in preparation of becoming the next vice president and ultimately president, if the media gets their way," he said Dec. 15. "Why hasn't she resigned yet? Because maybe, like all of us, she still thinks President Trump has a shot at victory, if only all the evidence of fraud can be proven and exposed."

There’s no evidence to back Stinchfield’s speculation. President-elect Joe Biden won the election, and electors across the country sealed his victory on Dec. 14 after weeks of litigation from Trump and his allies revealed no evidence of widespread fraud to change the results.

Harris’ decision to remain in the Senate for some time before becoming vice president is not unusual. She isn’t required to resign yet.

"No rule bars the vice president-elect from her day job representing California until she takes the oath on the 20th," said Terry Sullivan, a professor emeritus of political science at the University of North Carolina, Chapel Hill. "Then the constitutional ban on serving in two branches kicks in."

Anthony Rizzo, a spokesperson for Newsmax, said Stinchfield "was only speculating" as to why Harris had not left her seat. "He offered no conspiracy theory or claim she was not resigning for this reason," Rizzo said, adding that Newsmax recently declared Biden the president-elect.

The Biden transition team pointed to Harris’ public comments and tweets referencing Biden’s victory over Trump.

Some commentators who have made similar suggestions about Harris’ continued work in the Senate, including fellow Newsmax host Greg Kelly, noted that former President Barack Obama resigned from his own Senate seat in mid-November before moving to the White House.

Obama’s resignation was historically early compared with other officials in his shoes. According to the New York Times, he resigned earlier than any other president-elect or vice president-elect over the last 50 years who held public office at the time of his or her election.

"Al Gore resigned from the Senate on Jan. 2, 1993, and Joe Biden resigned from the Senate on Jan. 15, 2009," said Jack Beermann, a professor of law at Boston University.

There are several reasons why Harris may want to stay in her seat. It’s possible she is waiting for California Gov. Gavin Newsom, also a Democrat, to appoint her successor. Holding her seat also allows her to vote on Senate matters or participate in committee hearings.

Vice President-elect Sen. Kamala D. Harris, D-Calif., heads to the Senate chamber for a procedural vote on the National Defense Authorization Act in Washington on Dec. 11, 2020. (AP/ Applewhite)

"It would only be prudent for Harris to keep her Senate seat until she becomes a member of the executive branch at noon Jan. 20, 2021," said James Pfiffner, a professor emeritus in the Schar School of Policy and Government at George Mason University. "The Senate might conceivably consider important issues between now and then."

"If her vote were important, she could resign the morning of the inauguration," Beermann added.

Harris may also want to be present if Republican senators object in January to the counting of Electoral College votes in a longshot attempt to overturn the results of the election, experts said.

One reason a senator in Harris’ position might resign early is "so a successor will be ahead in seniority, which can eventually impact committee assignments," said Aaron Crawford, assistant editor of the Papers of Andrew Jackson at the University of Tennessee, Knoxville. 

Previous presidents and vice presidents have followed no clear pattern, the New York Times review shows. Vice President Mike Pence, for example, served as Indiana’s governor until Jan. 9, 2017, according to Indiana’s official state website.

Two other vice presidents who came into office after working in the Senate — Dan Quayle, who served with President George H.W. Bush, and Walter Mondale, who served with President Jimmy Carter — left their Senate seats in January and December, respectively.

One odd case occurred in 1961: Lyndon B. Johnson, a senator representing Texas, had run simultaneously for reelection to the Senate and for vice president on a ticket with President John F. Kennedy. He won both races. "He was actually sworn in (to the Senate) for the new term on Jan. 3 and then immediately resigned," Crawford said. 

RELATED: Jeanine Pirro suggests, without evidence, that Biden won’t be on Election Day ballot