The Senate is narrowly divided and Democrats hold a slim majority. But there’s no need for Ohio Sen. JD Vance, whom former President Donald Trump selected as his running mate Monday, to leave the chamber during the campaign.

       It makes sense to look to a senator as vice president: The role’s main official duty is to serve as president of the US Senate, although recent vice presidents don’t tend to spend too much time on Capitol Hill.

       In fact, there is a long history of presidential candidates selecting senators as running mates. President Joe Biden was at the end of a long career as a US senator from Delaware when he was tapped as then-Sen. Barack Obama’s running mate in 2008. Biden and Obama both continued to serve in the Senate during the campaign, as did Sen. John McCain, the Arizonan who was Republicans’ pick that year.

       Biden picked then-Sen. Kamala Harris as his own running mate in 2020.

       In 2016, Hillary Clinton picked Sen. Tim Kaine as her running mate. Kaine never gave up his seat and went back to serving as a senator after Clinton’s loss to Trump. In 2004, then-Sen. John Kerry, a Democrat, picked then-Sen. John Edwards as his running mate.

       So what does that mean for the seat? Usually, when a senator is elected as either president or vice president, they will resign from their Senate seat in early January after the election. Biden, however, is an outlier in this. He kept his Senate seat longer than most in early 2009, perhaps so that he could edge past some other former senators in the all-time Senate tenure list. Biden sits at No. 19.

       Vance won his seat in the Senate in 2022 and won’t be up for reelection as a senator until 2028. If he and Trump win in November, Vance would need to resign before taking the oath of office on January 20.

       It would then fall to Ohio Republican Gov. Mike DeWine, himself a former senator, to appoint a replacement until the next regular state election, when there would be a special election to fill the rest of the term.

       This can be a fraught process. Former Illinois Gov. Rod Blagojevich went to federal prison for essentially trying to trade away the appointment to fill out Obama’s term.

       For Biden, longtime aide and friend Ted Kaufman was appointed in 2009 to succeed him in the Senate. Kaufman did not run for the seat in his own right.

       California Gov. Gavin Newsom appointed Sen. Alex Padilla to succeed Harris in the Senate, and Padilla has since been elected to the seat.