Joe Biden continues to retain a fragile lead in the polls. Elizabeth Warren, his ascendant challenger, is not forcefully confronting him. Warren and Bernie Sanders, the progressive behemoths in the race, are not separating from each other.

Deep into the 2020 primary campaign — post-Labor Day and with three rounds of debates and fundraising quarters past — caution, patience and stasis have emerged as the defining traits of the Democratic contest.

Even as three candidates have pulled away from the rest of the field, early-state Democrats say it’s remarkable how none of them have truly taken command of the primary. They’re not seeing bold strategic strokes designed to distinguish their campaigns or sustained attempts to strike a decisive blow against rivals. And they don’t see an obvious front-runner with just 140 days until the Iowa caucuses.

“It’s really strange,” said Sean Bagniewski, the chairman of Iowa’s Polk County Democrats. “It’s strange that we’re this far along, we’ve been slugging it out, it feels like, for two years, we have this much interest, and there’s not really a clear favorite yet.”

Some have been counting on Sanders and Warren to better highlight their differences by now. Other Democrats were expecting a collision between Biden and Warren at last week’s debate — a confrontation that never materialized. Instead, a lower-polling candidate, former Rep. Beto O’Rourke, appeared to re-awaken. By the end of the week, Biden’s campaign was tangling with Julián Castro, who is polling at around 1 percent, over the appropriateness of Castro questioning Biden’s memory.

As one Democratic official in Iowa said of the field, “We’ve got a bunch of exceptionally talented people, a bunch of exceptionally talented vice presidents, cabinet members, DNC chairs. But there’s no president yet.”

One reason for the lack of clarity: for the most part, the top-tier candidates have adhered closely to their original battle plans, feeling little pressure to improvise or change direction. Warren’s approach has been slow and steady, ever-confident in the eventual payoff from her expansive field organization and detailed policy agenda. Biden’s campaign has shown few signs of panic in the face of gaffes and other candidate missteps.

But the lack of volatility in the campaign also reflects a caution informed by experience: Kamala Harris’s campaign surged in June following her criticism of Biden for his past opposition to busing and former associations with segregationist senators. But she quickly fell back. Castro, the ex-HUD secretary, has not benefited in public opinion polls from his rebukes of O’Rourke or, more recently, Biden. None of the candidates, in fact, who have singled out rivals for sharp criticisms — New York City Mayor Bill de Blasio and Rep. Tulsi Gabbard, among them — have seen big returns on their attacks.

A still-evolving primary issue set is also driving the measured approaches of the individual campaigns. Last week, O’Rourke — who had failed to gain traction in the campaign for months — drew newfound attention for his call for a mandatory buyback program for assault weapons. The candidates’ competing views on health care, a defining issue of the campaign, are only now becoming more clearly defined.

Sanders and Warren, flanking Biden on stage in Texas, battled over the differences in their plans. Biden noted that Warren has in the past asserted “I’m with Bernie,” on Medicare for All, then stressed that he supports keeping the Affordable Care Act but adding a public option. “I’m for Barack,” he said, before pressing Warren on whether she would raise taxes on the middle class to pay for the plan.

“I think clearly for the first time you had Bernie and Warren having to defend Medicare for All in a way they haven’t had to. Biden had help making that case from [Sen. Amy] Klobuchar and Mayor Pete [Buttigieg],” said Joe Trippi, a Democratic campaign veteran. “That’s the big defining issue. They’re going to have it out and that’s not going to happen in one night. That was the beginning of it. That was the first shots fired, the first volley — real volleys — I think you’re starting to get to the crux of the matter.”

Trippi said the vast majority of Democratic voters are still not tuned into the primary or even watching the debates. Those who are tuned in tend to have more hardened views behind a certain candidate.

“Anybody who thinks this thing is set is just not understanding a multi-candidate field like this,” Trippi said. “The only people paying attention are really interested people, who already love Joe Biden and think he’s the greatest, or already love Elizabeth Warren. They’re all watching to cheer their candidates. So when you attack someone else, you’re not going to score anything against them. That’s why when Castro attacks Joe, everybody pukes. It was the same mistake Harris made in the first debate.”

Comparing the primary to a marathon, Tom Perez, the chairman of the Democratic National Committee, said, “We’re at mile eight.”

With many top Democrats — like Perez — convinced that it’s still early in the campaign rather than late, one view holds that there is still a great deal of fluidity in the field.

“On the one hand, it’s clear that 60 percent of the voters are with the top three candidates, and that has been very stable,” said Rose Kapolczynski, a Democratic strategist who is unaffiliated in the race. “On the other hand, Biden and Sanders are not knocking it out of the park every day, and they aren’t growing.”

She said, “I still think there is a good chance that someone else emerges.”

Though six Democrats have already dropped out of contention and many others are on the brink, Bakari Sellers, Harris’ campaign co-chair in South Carolina, said it’s too soon to count out candidates who have time to catch on with voters.

“The reason that the top three are the top three is simple: there was a draft Warren movement since 2014, Bernie Sanders has been running for president since 2015 and Joe Biden’s been running for president since before I was born,” Sellers said. “A lot of these candidates are still learning who they are and defining themselves and now voters are finally paying attention.”

The primary campaign appears likely to become even more muddled over the next month. Biden appears no stronger — or weaker — than he did entering the last debate. Warren and Sanders have not appeared anxious to confront each other. Major donors in Texas were jockeying for photographs with Andrew Yang after the debate, while Sens. Amy Klobuchar and Cory Booker were both widely viewed as significantly more effective than in previous debates.

Jen O'Malley Dillon, O’Rourke’s campaign manager, said people only now “are starting to tune in,” predicting, as other candidates’ advisers have, that the race will remain fluid “through the winter.”

In remarks at a Houston fundraiser on Friday, Biden noted as much.

“The fact of the matter is for the first time we had something approaching a debate,” Biden told the crowd.