Former President Donald Trump and former Vice President Mike Pence have gone from unlikely allies to bitter rivals. Here's everything you need to know:
How did Trump's relationship with Pence begin?
Trump decided on Pence at the last minute. According to Politico, Trump "didn't particularly like Pence" when they first met, and "just four days before the  Republican National Convention," the unlikely nominee "was still waffling on who to pick as his running mate." Pence was a top contender, but so were New Jersey Gov. Chris Christie — the first 2016 presidential candidate to drop out to endorse Trump — and former House Speaker Newt Gingrich, who was still angling for the job.
"I told [Trump] ... he could have two pirates on the ticket or a pirate and a relatively stable and normal person," Gingrich said during a Facebook Live Q&A. Trump liked the sound of that.
Per Politico, the devout Pence helped Trump's poll numbers with evangelicals who were uncomfortable with the mogul's checkered past, but "Pence felt a lot like the medicine Trump didn't want to choke down." However, thanks to the machinations of Paul Manafort and a flat airplane tire that stranded Trump in Indianapolis for an extra night, choke it down he did.
Writing for The Week in 2019, Matthew Walther pointed out that Trump's barnstorming style and populist platform were always an odd match for Pence's plainspoken manner and passé neoconservatism. "This is exactly why Trump chose Pence to be his vice president. He is a throwback, and a useful one," Walther wrote.
What was Pence's role in Jan. 6?
Trump called Pence on the morning of Jan. 6 to urge him, one last time, not to certify Biden's victory. Witnesses said Trump got "heated" and told Pence he would "either go down in history as a patriot" or as "a pussy."
Trump's pleas fell on deaf ears. In a letter to Congress, Pence rejected the idea that "the Founders of our country intended to invest the vice president with unilateral authority to decide which electoral votes should be counted."
When the Capitol riot began, several members of the mob chanted "hang Mike Pence," while others erected a makeshift gallows. When Trump heard the chants, he told White House staff that Pence "deserves" it, former aide Cassidy Hutchinson told the House committee investigating the Jan. 6 events. As rioters stormed through the Capitol building, Trump tweeted that Pence "didn't have the courage to do what should have been done."
One White House security official testified that Pence's Secret Service detail began "to fear for their own lives" as they scrambled to secure an evacuation route for the vice president. "There were calls to say goodbye to family members, so on and so forth," the official said. Pence was taken to a secure location but refused to leave the Capitol complex entirely. Just after 8:00 p.m., Pence reconvened the Senate, and by 3:30 a.m., Biden's victory had been certified.
What's happened to their relationship since then?
Nothing good. Rep. Jim Banks (R-Ind.) told CNN in Feb. 2021 that Pence had spoken to him "very favorably about his relationship" with Trump, giving Banks "the sense they speak often and maintain the same personal friendship and relationship now that they have for four years."
Even if that was true at the time, it doesn't seem to be anymore. In Feb. 2022, Pence again rejected the idea that he could have handed the election to Trump. "I heard this week that President Trump said I had the right to 'overturn the election.' President Trump is wrong. I had no right to overturn the election," Pence said at a Federalist Society event. The idea "that any one person could choose the American president" is "un-American," he continued.
Is there precedent for presidents and vice presidents not getting along?
Plenty. In the early years of the republic, whoever received the second most electoral votes would become vice president. This led almost immediately to the acrimonious cohabitation of Federalist John Adams and Democratic-Republican Thomas Jefferson. Then, after attempting to steal the election of 1800, Aaron Burr allegedly tried to start his own country out west and ended up on trial for treason, with Jefferson "fully intending to hang" his former VP, Ranker notes.
The constitution was quickly amended to ensure that presidents could choose their own vice presidents, but egos still clashed. John C. Calhoun resigned as Andrew Jackson's vice president in 1832 after a dispute over states rights. Jackson later threatened to "secede" Calhoun's head "from the rest of your body" if he attempted to lead South Carolina out of the Union. (This technically makes Trump at least the third president to have responded positively to the idea of his ticket-mate being executed).
Several other president-VP relationships were adversarial, but not life-threateningly so. Richard Johnson, who served under Martin Van Buren, was dropped from the ticket in 1840 after disappearing from D.C. for nine months to run a tavern in Kentucky. Franklin Roosevelt got himself drafted for a third term to avoid being succeeded by Vice President John Nance Garner, who opposed the New Deal. Al Gore and Bill Clinton left office on bad terms, with Gore blaming Clinton for his loss in the 2000 election.
What's next for Pence and Trump?
Pence appears to be setting his ambitions higher than another four-year stint at the Naval Observatory. The former VP has pitched himself to the billionaire DeVos family as a potential 2024 presidential candidate and has "repeatedly traveled to meet with donors and operatives" in South Carolina, The Washington Post reported last month. Marc Short, Pence's longtime chief of staff, told the Post that Pence and his family plan to make a decision about 2024 "[a]t some point early next year."
Polls suggest that Pence would struggle to mount a serious challenge against the former president. Trump dominated a recent Morning Consult poll of potential Republican primary candidates, in which he won 52 percent of the vote, followed by Florida Gov. Ron DeSantis with 21 percent and Pence with just 8 percent.
Pence has also clashed repeatedly with Trump during the midterms, with the two endorsing rival candidates in several primary races. On Friday, the two held dueling rallies in Arizona, with Trump backing former television anchor Kari Lake in the state's gubernatorial primary while Pence threw his support behind businesswoman Karrin Taylor Robson.
The major split between the two candidates is over the 2020 election. Robson has taken a moderate line on Trump's stolen election claims. She's willing to blame liberal judges and big tech companies for tilting the election in Democrats' favor, but "has stopped short of saying Trump lost because of fraud," The Associated Press notes. Lake, on the other hand, is all in. She's even called for Arizona Secretary of State Katie Hobbs (D), who oversaw the 2020 election in Arizona, to be imprisoned.
Pence told the crowd that Trump and his allies "want this election to be about the past" and that if the GOP "allows itself to be consumed by yesterday's grievances, we will lose."
CORRECTION: An earlier version of this article incorrectly identified Rep. Jim Banks (R-Ind.) as a congressman representing Arizona. This has since been corrected. We regret the error.