At last, Democratic voters will get the faceoff many have been waiting for: Joe Biden and Elizabeth Warren on the same presidential debate stage for the first time.

With that, a fork in the road is coming into view for the Democratic Party.

Only 10 candidates qualified for the Democrats’ September debate by the Wednesday deadline. ABC, the sponsoring network for the event, had announced that would mean just one night of debating, Sept. 12.

Two top candidates — the former vice president who is the front-runner, and the Massachusetts senator whose campaign has been gathering momentum — personify big choices Democrats face about what they stand for and how much change will be needed if they oust President Donald Trump.

Warren wants to shake things up, Biden wants to calm things down. She calls for tectonic changes in the U.S. economy and politics. He proposes more incremental reforms.

For many, Biden is the candidate of the head, with voters drawn not by passion, but by the belief he is their safest bet to beat Trump. For others, Warren is the candidate of the heart, drawing thousands of chanting fans to rallies who shrug off doubts about her electability.

With Warren rising steadily in polls to gain a place in the top tier of candidates — closing in on Biden and her rival on the party’s left, Sen. Bernie Sanders of Vermont — many Democrats foresee a Warren-Biden collision at the end of the primary election trail.

“Do Democrats want someone as radical — radical in a good sense — as Franklin Delano Roosevelt proposing fundamental change, or someone like Biden proposing normalcy or continuity,” asked Robert Kuttner, progressive author of a forthcoming book “The Stakes: 2020 and the Survival of American Democracy.”

Elaine Kamarck, a member of the Democratic National Committee who has not endorsed any candidate, said she believed Warren “is the one person in the race who could overtake Biden. I could see it going down to a two-person race.”

Democrats are a long way from that point. Biden still leads by double-digit margins in most polls. And it is hard to see how Warren can succeed unless Sanders, who still ranks second in most polls, fades.

When the DNC standards were more lenient for the June and July debates, 20 candidates qualified and were split into two debates of 10 candidates each. In neither of the first two rounds did Biden and Warren get placed on the same stage.

For the September and October debates, the DNC toughened its qualifying requirements. That left all but 10 on the outside looking in. Beyond Biden, Warren and Sanders, Sens. Kamala Harris, Amy Klobuchar and Cory Booker qualified, as did South Bend, Ind., Mayor Pete Buttigieg, former Housing secretary Julián Castro, former Rep. Beto O’Rourke and Andrew Yang, the tech entrepreneur.

Among the non-qualifiers, Tom Steyer, the billionaire political activist, came the closest. Under the DNC rules, he would make the October debate if one more qualifying poll shows him with at least 2% support.

As for Warren and Biden, the two have not been taking direct shots at each other, and it’s not clear they will do so on the debate stage together.

Asked about debating Warren, Biden said Wednesday, “I’m just going to be me, and she’ll be her, and we’ll let people make their judgments. I have great respect for her.”

Still, the two have been taking veiled swipes that foreshadow the collision to come.

In a speech to the Democratic National Committee in San Francisco last week, Warren’s target was unmistakable:

“Some Democrats in Washington believe the only way forward is to make change incrementally, a few tweaks here and some nudges there,” she said. “No. This is a time of crisis. … I’m here with a message for Democrats: This is not the time for small ideas.”

In his latest television ad, Biden criticized unnamed backers of “Medicare for All.”

“Obamacare is personal to me,” he said in the ad. “When I see the president try to tear it down and others propose to replace it and start over, that’s personal to me. We have to build on what we did.”