Hillary and Bill Clinton have been at the center of U.S. politics for the last-quarter century; for more than 100 years only Richard Nixon showed such durability.

Now, as Democrats face their worst crisis since the 1920s, it’s time for the Clintons to ride into the political sunset. New ideas and new faces need to emerge. Despite Hillary’s graceful concession speech and some of the virtues of her campaign, many Democrats believe her shocking loss to the unpopular Donald Trump was in no small part self-inflicted.

The Democrats, who see themselves as the governing party, are in deep despair. Republicans will control the White House, both chambers of Congress, with the prospect of making the Supreme Court more conservative. Republicans also control two-thirds of the state houses.

The losing party faces an internecine ideological battle, as the Elizabeth Warren and Bernie Sanders left-wing insist they need a sharper, better-defined populist agenda and more moderate Democrats argue for a more centrist message.

In the Senate, where Democrats will hold 48 of the 100 seats, the new minority leader, Chuck Schumer of New York, will try to keep a foot in both camps. There will be real tensions, though opposition to Trump may be a galvanizing force.

When it comes to politics, the conventional wisdom has held that the Republicans had depth and the Democrats a weak bench. The Republican bench was a mirage; think Gov. Chris Christie of New Jersey. With President Barack Obama and Vice President Joe Biden in the White House and the Clintons prepared to follow them, there was no room for younger Democrats to surface.

Looking ahead, there are a number of potentially appealing Democrats who need to rise to the fore. Warren and Virginia Sen. Tim Kaine, Clinton’s moderate running mate, will be two of the more visible faces in the ensuing debates within the party. Among the others are senators Michael Bennet of Colorado, Chris Van Hollen of Maryland, Amy Klobuchar of Minnesota, Corey Booker of New Jersey and Kirsten Gillibrand of New York. There are promising younger House members; one of the few governors is John Hickenlooper of Colorado. Democrats need to create forums for mayors and governors-in-waiting and let ideas bubble up.

They should reject two truly stupid notions. One is to make the fight over the next Democratic Party chair central to the direction of the party. The need is for a smart technician who can raise money and is presentable on television. When has either national committee been central to formulating agendas or ideas?

The next bad idea would be to look for their version of Trump, an outsider who has no connection to Washington and can fire up grass-roots voters. Using Trump as a role model is absurd, as is trying to rule out anyone with governing connections.

The populist vs. mainstream debate is already raging: What policies can appeal both to the younger and more diverse elements of the party and win over a small percentage of working-class whites?

Inevitably that discussion gets back to this year’s presidential campaign. Should Hillary have fashioned a more populist appeal to those Rust Belt voters? Other than competence and experience, and the other guy is a bum, she lacked a compelling message.

There were good elements of the Clinton campaign: She assembled a first-rate staff, was a prodigious fund-raiser, offered serious and sensible policy proposals, and ran a near perfect convention; and in three debates, though they proved largely irrelevant, she dominated Trump.

Many Democrats, including Hillary Clinton, are pinning the defeat - she won the popular vote but unexpectedly lost Pennsylvania, Wisconsin and probably Michigan - on Federal Bureau of Investigation Director James Comey, who bowed to Republican pressure and injected the Clinton email controversy into the campaign in the final 11 days.

Sure, but the email problem from start to finish was self-inflicted. She never should have used only a private email server as secretary of state. Then, when the misstep was revealed, she should have been more forthcoming and apologized immediately.

Finally, Comey’s role was magnified by Bill Clinton’s foolish meeting with Attorney General Loretta Lynch on an airport tarmac in June.

The attorney general oversees the FBI director. But after the meeting was disclosed, she recused herself from the email investigation. If that hadn’t occurred the FBI would have simply announced last July that there was no cause for criminal charges against Clinton and there would have been no last-minute report of a separate inquiry that ultimately turned up nothing.

The Clintons have given Democrats, and the country, many triumphs and too many traumas. The balance sheet is favorable. But there isn’t room for any more traumas.

There are senior figures, Obama and Biden, who should play a big role as the party tries to recover. Obama leaves office at 55, a much respected and popular figure. In a poll immediately before Election Day, Bloomberg Politics found that in a match-up against Trump, Obama would have run almost 10 points ahead of Clinton. There’s little doubt he would have won Pennsylvania, Wisconsin, Michigan and probably Florida and North Carolina, and trounced Trump.

— Albert Hunt is a Bloomberg columnist.