Democrats are bracing for a months-long, drawn-out primary fight featuring several viable candidates that could drag into the summer.
That scenario is prompting the campaigns, several of which have signed up veteran delegate counters, to begin strategizing for a protracted nomination slog, with some even playing out scenarios for dealmaking in the weeks leading up to the Democratic convention in July.
"What's different is the number of candidates who can lay claim to being serious enough to win delegates," said Elaine Kamarck, a member of the party's Rules Committee and the author of the book "Primary Politics." "That alone can result in someone with a plurality."
The anxiety is the result of an unusually wide open race. Less than three months before Democrats cast their first primary votes, none of the party's presidential candidates is polling regularly above 30 percent. At least four are on track to earn delegates in Iowa. And now, former New York mayor Mike Bloomberg, one of the world's richest people, says he might spend hundreds of millions of dollars to attract voters down the stretch.
Broadly, the Democrats' fear is that the surging energy and turmoil in their party, and its passion to defeat President Donald Trump, may be leading to fracturing rather than unity. Some in the party worry that could hamper its ability to defeat Trump, although others argue that a tough primary will strengthen the eventual nominee.
Three party veterans, who have each worked on delegate strategies in past presidential contests and spoke on the condition of anonymity because of their current positions, described the landscape as unprecedented.
"I have never seen a situation where the likelihood that this thing will go to a convention without a candidate having a majority of the delegates is higher than it is today," said one of the strategists, who assumes Bloomberg will formally enter the race and win some delegates. "You will have multiple winners at the front end, none of whom will match the resources of a person at the end of the process."
The operatives point to other factors, including the increasing role of small-dollar fundraising, which allows candidates to stay in longer, and the diminished role of superdelegates, whose function was to rally the party around a nominee if needed.
They point, also, to Sen. Bernie Sanders' medical and political rebound from a heart attack, which suggests he could battle Sen. Elizabeth Warren for liberal voters for months. One delegate counter admitted to concluding it is now "more likely than not" that no one gets a majority of pledged delegates, largely because of Sanders' continued strength and the likelihood that he will continue to campaign even if he is trailing late in the primary contest.
This is a starkly different landscape than the last two protracted Democratic battles, when Barack Obama bested Hillary Clinton in 2008 and Clinton outlasted Sanders in 2016, several strategists said.
"In the past two contested fights of 2008 and 2016, they were two-person races, and in a two-person race one inevitably has a majority," said Jeffrey Berman, a delegate counter and Rules Committee member who recently worked for former congressman Beto O'Rourke's campaign. "Once you get a third candidate in the race that is pulling delegates away, then you start looking at the possibility of no candidate having a majority."
The scenario is by no means certain. Democrats have a history of rallying around early winners, and polls are almost certain to shift in the coming weeks as Democratic voters begin to solidify their preferences. There is also an overwhelming desire in the party to find the single candidate best able to take on Trump, which could increase the pressure for candidates to drop out if they have no clear path to a majority.
The Democratic votes kick off Feb. 3 with the Iowa caucuses, followed quickly by contests in New Hampshire, Nevada and South Carolina. Those states have widely different demographics, so three or even four candidates could emerge from the early phase with victories under their belt.
That leads to Super Tuesday on March 3, when more than a dozen states, including delegate-rich Texas and California, will cast their votes.
Sanders' campaign, for one, is operating on the assumption that the party will coalesce after those early votes and that Bloomberg's money will have little impact later in the process.
"I think you come out with one or two candidates out of Super Tuesday," said Jeff Weaver, a senior adviser to Sanders. "The proportional delegate system that the Democratic Party uses makes it difficult to make up a lot of lost ground once you fall behind." Under party rules, states do not award all their delegates to a single winner but divide them among all who meet a certain threshold.
Yet the idea that at least three viable candidates will emerge from Super Tuesday has become a working assumption for other presidential campaigns, including that of former vice president Joe Biden, who leads in national polls but has fallen behind in Iowa surveys.
Greg Schultz, Biden's campaign manager, has argued that the Biden coalition, which comprises a diverse geographic and racial constituency, would fare well in a drawn-out process, when the battle could hinge on who wins delegates in particular congressional districts.
"Math is on our side when it comes to diverse popular support and the pursuit of delegates, and delegate math is a cornerstone of our strategy," Schultz said. "We have a broad coalition, and the way we ensure our success is by keeping as many of the different buckets of the Democratic Party, by plurality, supporting Joe Biden."
Bloomberg's advisers, who have announced the former mayor would skip the first four state contests if he runs, also believe the field is likely toremain split between three or more viable candidates after those states have their say. The continued strength of both Sanders and Warren is a key to that calculation.
"The progressive wing is split," said a Bloomberg adviser who spoke on the condition of anonymity to discuss strategy. "If that lane was consolidated, it would be more difficult."
For all the campaigns, a close study of the Democratic Party's often-obscure rules has now become mandatory, with several campaigns employing specialists to work out the esoterica of where to campaign and how to spread resources.
The first phase of the nomination process is often a game of expectations, based on intangible concepts like buzz, momentum and energy. The second phase, which begins Feb. 3, is about hard numbers, and one number matters far more than the others: 15 percent.
That's the qualifying level for earning delegates to the Democratic convention, and it is imposed on both the statewide and congressional district level. States award most of their delegates based on a candidate's performance in individual districts; districts that have more Democratic voters receive more delegates.
"Three candidates being over 15 is really the thing that creates the likelihood of a brokered convention," said the veteran Democratic delegate strategist who now expects an inconclusive result. "The reason a brokered convention is more likely than not these days is really Bernie Sanders more than Michael Bloomberg."
The notion of a brokered convention can conjure up images of impassioned floor fights, backroom deals and frenetic horse trading between candidates. The more likely scenario in the current era, political experts say, is that any such negotiation would unfold in the weeks leading up to the convention, so that by the time of the gathering, July 13-16 in Milwaukee, the nominee's identity would be clear.
Delegates are selected with the approval of the candidate who wins them. But they are not bound to vote for that candidate, allowing for defections or for a candidate to instruct his delegates to support a rival.
The last significant three-way delegate contest in the Democratic Party took place in 1984, when Rev. Jesse Jackson won about 18 percent of the available delegates, compared to 38 percent for former vice president Walter Mondale and 36 percent for Sen. Gary Hart of Colorado.
Mondale won the nomination at the convention largely by grabbing the support of a majority of superdelegates - party leaders and dignitaries who have voting rights at the convention.
Under rule changes since the 2016 election, superdelegates will still be seated at the 2020 convention, forming 15 to 20 percent of the delegate pool, but they cannot vote on the first ballot if that would decide the outcome.
The change was made in part due to complaints of a "rigged" system by Sanders supporters in 2016. It removes a fail-safe that was designed to avoid a drawn-out convention battle, possibly increasing the pressure on candidates to strike a deal before the convention if no one has a majority.
That could lead to unity tickets, either among liberal or moderate candidates, or it could give more minor candidates with just a few delegates a major role in the outcome.
Although the scenarios for a volatile convention are remote, they have begun worrying some Democratic insiders. Superdelegates can still vote on the second ballot, adding an element of unpredictability to the negotiations, especially if a candidate like Sanders, who has strained ties to the party establishment, is still in the hunt for the nomination. Biden's team has expressed confidence that the superdelegates would rally around him on a second ballot.
To avoid such divisive scenarios, Democratic leaders and activists could try to settle on a nominee sooner. More than half of the available pledged delegates are scheduled to be awarded over three consecutive Tuesdays in March, making calls for party unity a likely focus of the campaigns.
Several activists have already begun voicing their concern that a delay in picking the nominee - and the resulting intra-party bitterness - could hand Trump a gift in the general election.
"I think it could be a disadvantage, because you won't have a decision until late in the game," said David Brock, a Democratic strategist who has raised $30 million through a group called American Bridge to run ads against Trump. "It is a recipe for a divided party."