The Republican nominees in five of the past six Presidential elections have disappeared from the face of the earth. Not literally, of course; Mitt Romney, George W. Bush, Bob Dole, and George H. W. Bush are all still alive. But all of them are gone from the political scene, absent at conventions, even the most recent inauguration. This is not a coincidence or a generational quirk. Rather, it reflects a fundamental problem with the contemporary Republican Party.

Bill Clinton likes to say that Presidential elections are about the future, not the past. This is only partly true. Voters see previous Presidents as templates for those who may follow. Republicans understood this better than anyone. They spent decades vying for the mantle of Ronald Reagan and disparaging their opponents as the heirs of Jimmy Carter. This was smart politics: Reagan was widely perceived as a successful President and Carter as a failure, and the message resonated.

But Reagan left the Presidency about a quarter century ago, and anyone who voted for him is now middle-aged or older; young and even not-so-young people have little or no memory of him in office. This is also true of Carter, who is probably better known today for his good works in monitoring elections and building houses for the poor than for his Presidency.

But what, then, did Republicans offer in subsequent decades? George H. W. Bush was voted out of office after a single term, in 1992. Dole was already a senior citizen in 1996, and left the public stage soon after his defeat. (His wife, Elizabeth, also served a single term in the Senate before she was defeated.) George W. Bush won a controversial race in 2000 and was reëlected in 2004—but his Presidency is largely remembered for an economic collapse and a tragic war. Romney lost last year and has hardly been seen since; he seems likely to disappear from political life.

Compare that record to the Democratic candidates of the period. Clinton won in 1992 and 1996, and remains a major force. He was a critical figure in President Obama’s reëlection last year, and is, of course, known today as Hillary Clinton’s husband—and she is the most popular politician in America, as well as the front-runner in the 2016 race. Since 2000, Al Gore has accumulated immense stature as the public face of climate change, sharing the Nobel Peace Prize, in 2007. He also made a fortune in business. John Kerry, the 2004 nominee, soldiered on in the Senate after his defeat and rebuilt his career—he is now Secretary of State. Obama has won twice, with commanding majorities of the electoral vote.

John McCain, the 2008 nominee, is the single recent Republican who did not follow his Presidential run by punching a ticket to obscurity. And he demonstrates the importance of continuing to have a real job in politics. At the age of seventy-six, McCain is no longer a prospective President, but he remains an important member of the Senate, as well as something close to an official spokesman for his party, especially on defense and foreign policy. (For example, McCain is a fixture on the Sunday talk shows; his fellow former nominees never seem to appear.) One can listen to McCain and imagine a kind of leadership very different from the one we currently have.

George W. Bush, in contrast, gives the Republicans their own version of the Jimmy Carter problem. Some Republicans criticized Obama for campaigning in 2008 and 2012 as if Bush were still on the ballot, but from a political perspective Obama probably did not run hard enough against Bush, who is much less popular than Carter. It’s true that Americans generally soften toward their Presidents over time, but a George W. revival does not appear imminent. It’s hard to imagine that many voters in 2016 will be pining for a restoration of the Bush years. (This could be an especially pressing problem for one prospective candidate in 2016, George W.’s brother Jeb.)

It’s true, too, that voters didn’t exactly want Clinton back in office, and probably will not want what would be seen as a third Obama Administration in 2016. Whether Obama’s second term is a triumph or a disaster or something in between is, of course, the great unknown at this point. (And the place of Vice-President Joseph Biden in the Presidential mix is similarly mysterious.) But, at the moment, it does appear that voters will be able to see in Obama, as they did in Clinton, as someone who succeeded as President or, at least, did well enough. Republicans have no such recent model. And that problem isn’t going away.

Illustration by Justin Sullivan/Getty.