Every controversy enveloping President Donald Trump spurs Democratic optimism about their party’s future prospects. And just as the maneuvering for 2020 has started, so too has speculation about likely nominees.

Based on recent presidential campaign history, the ultimate Democratic winner might well be one of those making early trips to Iowa or New Hampshire. But early polls and dope sheets will almost certainly be wrong or at least misleading.

More likely than not, the next president, to be elected in either 2020 or 2024, will be someone barely on the current radar screen. (Trump has already begun his own re-election race, but Republican 2020 speculation may be even less predictable than Democratic.)

Just look back four years to the initial jockeying to succeed Barack Obama. A 2013 fivethirtyeight.com analysis of early 2016 polling showed Sen. Marco Rubio of Florida leading 13 other Republicans. Not even mentioned: Trump, who even then was thinking of running but was not being taken seriously.

Among Democrats, former Secretary of State Hillary Clinton was the overwhelming front-runner, as she had been eight years earlier when she wound up losing to Obama. The seven others with some support did not include Sen. Bernie Sanders, the Vermont independent who nearly took the nomination from Clinton in 2016.

The next Democratic race will probably resemble the large 2016 GOP field, attracted by Trump’s low approval numbers and his failure to expand his political base into believing that one of them will win in 2020. In a recent Fox News poll, a significant majority said they’d likely vote for someone new against Trump.

Those numbers, of course, are hardly more meaningful than the recent analysis by CNN’s Chris Cillizza, listing 22 potential Democratic candidates, of whom three he said have “a real chance to win the nomination” if they run: Sanders, former Vice President Joe Biden and Massachusetts Sen. Elizabeth Warren. Sanders will be 78, Biden 77 and Warren 70 in 2020, and many Democrats will want someone younger.

His list’s main value may be its inclusiveness, though he omitted such rising younger Democrats as former Missouri Secretary of State Jason Kander and South Bend, Ind., Mayor Pete Buttigieg, who might satisfy voters’ likely desire for someone new.

He included six senators, six current and former governors, two mayors, one House member, plus four business executives, including Facebook’s Mark Zuckerberg and Dallas Mavericks owner Mark Cuban.

Of the best known three, it’s unclear which, if any, will run, though Sanders may be best in position to influence the race with the large organization he is building.

The more interesting names were on Cillizza’s list of eight with “potential to be a major contender.” They included two senators already making quiet 2020 moves, New Jersey’s Cory Booker and California’s Kamala Harris; two governors showing definite signs of interest, New York’s Andrew Cuomo and Virginia’s Terry McAuliffe; 2016 vice presidential nominee Tim Kaine; little known Washington Gov. Jay Inslee; and, perhaps most interestingly, comedian-turned-Minnesota Sen. Al Franken and Connecticut Sen. Chris Murphy.

Of those, Booker seems the likeliest to run, McAuliffe and Murphy perhaps the most promising. Kaine lacks a political base, and Cuomo and Harris might be ill-suited for the retail politics of Iowa and New Hampshire.

Franken’s Minnesota colleague, Sen. Amy Klobuchar, who recently headlined an Iowa Democratic fundraiser, was in a secondary group rated as having “a chance.” It also included former Maryland Gov. Martin O’Malley, who never stopped running after flopping in 2016; and Colorado Gov. John Hickenlooper. Lastly were the rich business people like Cuban, Zuckerman and Sheryl Sandberg.

If I were betting, I’d take the field against Biden, Sanders and Warren. And I’d watch carefully for early responses in Iowa or New Hampshire to any of these lesser known figures - or perhaps someone else as yet unmentioned. Sanders’ May 2015 Iowa crowds were the first sign he might become a major 2016 player.

Despite the Trump experience, early efforts have been a tipoff ever since John F. Kennedy decided to seek the White House right after narrowly losing the vice presidential nomination at the 1956 Democratic Convention.

Another valuable sign: look for the non-Trump. Voters tend to pick someone clearly different from the incumbent. For the Democrats, that means someone younger with governmental experience and less of an alpha male.

Like most out of power parties, the Democrats are leaderless now. That ultimately will change. And it won’t stop pundits and pollsters from producing multiple analyses of which one might emerge.

But the meaningful ones may only be evident in retrospect.