On July 4, Rep. Justin Amash declared his “independence” from the Republican Party, and he now plans to run for reelection as an independent (or maybe he’ll pursue a presidential bid). And although Amash has said he’s “very confident” he can hold onto his House seat while running as an independent, that would be pretty unusual, at least historically speaking.

Since 1950, only five sitting members of Congress have voluntarily left a major party to become an independent, according to Antoine Yoshinaka, a political scientist from the University at Buffalo who wrote a book on party-switching. And of those five, only two of them sought reelection as independents. To be clear, this count does not include members like Sens. Joe Lieberman (2006) or Lisa Murkowski (2010), who lost renomination in their party primaries and then continued their reelection bids as an independent (Lieberman) or as a write-in candidate (Murkowski).

Few leave a major party to become an independent Sitting members of Congress who switched from a major party to become an independent prior to their next election, since 1950 Member State Chamber Party switch year Next election Result Wayne Morse OR Senate R to I 1952 — — I to D 1955 1956 Reelected Harry Byrd Jr. VA Senate D to I 1970 1970 Reelected Bob Smith NH Senate R to I 1999 — — I to R 1999 2002 Lost primary Virgil Goode VA House D to I 2000 2000 Reelected Jim Jeffords VT Senate R to I 2001 2006 Retired The chart includes members who became independents while in Congress. It excludes the members who sought renomination with a major party but then ran as an independent or write-in candidate after losing their primary. It also excludes individuals who switched parties while out of office but later returned to Congress. Sources: Antoine Yoshinaka, Biographical Directory of the U.S. Congress

Running as an independent doesn’t tell us that much about Amash’s reelection chances, but of the two data points we do have, it’s probably safe to say that Amash won’t encounter the same conditions that existed for Harry Byrd Jr. in 1970 and Virgil Goode in 2000, the two party-switching independents who successfully sought reelection. And that’s because even though Goode said he was leaving the Democratic Party, he said he would align himself with the GOP, so he didn’t face any Republican opposition in 2000. Amash, on the other hand, doesn’t seem intent on aligning with either the Republicans or Democrats. Notably, Goode’s stint as an independent was short-lived; he switched from being an independent to the GOP in 2002. And in Byrd’s case, conservatives of all stripes rallied around the former Democrat — even many Republicans preferred Byrd to the GOP nominee. Amash, of course, is unlikely to enjoy such bipartisan appeal in a polarized political era. It probably also helped Byrd that his was a giant name in Virginia — his father essentially ran the state for nearly four decades.

Of course, there are a handful of individuals who have won races for Congress as outright independents from the start — including current Sens. Angus King and Bernie Sanders — or those who won their first races as independents but then switched to a major party right after winning, a phenomenon Yoshinaka called “pseudo-switching” in his book. But again, these cases all differ from the situation Amash is in.

For Amash, he switched parties partly because of sincere disagreements he had over the direction his party was moving in, but his maneuver also had an element of self-preservation: Amash had called for an impeachment inquiry against President Trump, putting him way out of step with the GOP, and it looked as if he faced a difficult renomination race in 2020. For example, an early June poll found him trailing one primary challenger, state Rep. Jim Lower, 49 percent to 33 percent, and a host of other Republicans have gotten into the race (both before and after Amash’s decision to leave the GOP).

But Yoshinaka told me that the opposition Amash faces from his former party isn’t that shocking, especially now that he’s decided to run as an independent. “One reason why it’s generally difficult for a member to shed a party label is that the switcher typically faces stronger-than-normal opposition from his or her previous party in the immediate aftermath of the switch,” Yoshinaka said. “Their former supporters will be extremely eager to defeat them, especially in their first attempt at reelection.” And in light of Amash’s standing among Republicans and the associated difficulties with seeking renomination, running as an independent might give Amash his best shot of winning reelection, considering his resources and built-in name recognition.

However, running as an independent means Amash will likely face both a Republican and a Democrat in November 2020. One reason why things worked out for Byrd and Goode is that they faced little or no opposition from one major party, respectively, when they sought reelection as independents. But Amash could have a true three-way race for a seat that while Republican-leaning — Trump carried it 52 percent to 42 percent in 2016 — still has a sizable number of Democrats. Yoshinaka pointed out that both parties will probably view the election as winnable, so they’ll expend resources in the district. “As a result, I’d be surprised if he were to win reelection as an independent, though of course it’s not impossible,” Yoshinaka said. In today’s polarized political environment, it also will be difficult for Amash to attract many dissatisfied Democrats and Republicans.

Still, Amash has another option — he could run for president. This is not to say he could actually win the White House as an independent or Libertarian, but if he has bigger political ambitions, his party switch might make more sense in the context of a national campaign. Yoshinaka said he could see an Amash presidential campaign raising the congressman’s profile, noting that while it’s hard to say exactly what Amash’s goal(s) would be, “it’s very rare for a politician to switch parties only to then retire and never to be heard [from] again,” especially as “ambition is a big driver of these sorts of decisions.”

One way or the other, it won’t be easy for Amash to win an election in 2020. But if he stays in the race for his House seat, Amash will be a rare party-switching independent seeking reelection who could give us a fascinating three-way race for the House.