From the moment former Vice President Joe Biden threw his hat in the ring, he has been the dominant front-runner in the race for the Democratic presidential nomination. That status was confirmed in the most recent ScottRasmussen.com poll of the race, showing Biden with 39% of vote and a 19-point lead.

His nearest challenger — Sen. Bernie Sanders — attracted just 20% support, and nobody else reached double digits.

But in a party that has become younger and more racially diverse, it’s never seemed likely that two white men over 70 would have the field to themselves. The question all along has been which of the other 20 or so candidates might move into the top tier.

It’s certainly early, but it may be that Sens. Elizabeth Warren and Kamala Harris are gaining the traction they need to make it a four-person race. In our latest poll, they finished third and fourth with 8% and 6% of the vote, respectively. That’s a long way back, but both Warren and Harris offer Democrats a much-needed contrast rather than limiting the options to a pair of older white men.

Not only that, the poll found that Sanders, Harris, and Warren are the top three second choices for Biden voters. Biden, Warren, and Harris are the top second choices for Sanders’ voters.

When you add up the first, second and third choices for Democratic voters and Democratic-leaning independents, Biden makes the top three for 66%. Fifty-one percent put Sanders in that category. Warren is a top-three pick for 33%, while Harris is selected by 29%. Nobody else reaches 20%.

Other survey data found that 85% of Democratic voters and Democratic leaning Independents would be excited or satisfied with Biden as the party’s presidential nominee. That’s a pretty amazing total, but Biden is not alone. A ScottRasmussen.com national survey found that 77% would also be satisfied with Sanders. Seventy-three percent say the same about Harris and 71% about Warren.

Only 4% to 6% would be depressed with any of those candidates as the party nominee.

Looking through the data, it’s clear that former Congressman Beto O’Rourke and South Bend, Indiana, Mayor Pete Buttigieg aren’t all that far behind Warren and Harris. But other than being young, neither of those men offers a compelling rationale for why they should be considered instead of Biden or Sanders. And neither of them has all that much experience in office to draw upon.

At the moment, therefore, it looks like the Democrats have a four-person race. Biden is the front-runner, and the race is his to lose. Sanders has a core following from the last time around, but there are questions about whether he can appeal to a wider base. Warren and Harris are making their first run for the White House and appear well positioned to shake things up when voters begin to pay attention.

Scott Rasmussen is the publisher of ScottRasmussen.com. He is the author of “The Sun Is Still Rising: Politics Has Failed But America Will Not.”