Since entering the race last spring, former Vice President Joe Biden has consistently led the Democratic field in national polls. By almost any measure, he remains a top-tier candidate for his party's nomination.
But in Iowa, which will hold the first contest of the Democratic primary next year, some of Biden's rivals have caught up to him or surpassed him in recent polls. And in interviews with a dozen top Democratic leaders, officials and strategists, many expressed concerns about Biden's standing in Iowa.
"I wouldn't count him out, but there's certainly been some troubling signs," said former Democratic political operative Grant Woodard, who worked on Hillary Clinton's 2008 Iowa campaign. "I think they started with the wrong attitude here and came in as trying to get people to accept inevitably. I always think that's dangerous for people to do."
"There's certainly flashing lights going on," he added.
According to the latest, Biden is down eight points in Iowa from June to November to leave him tied with Senator Bernie Sanders at 22% as the top choice among registered Iowa Democrats. They were just ahead of South Bend Mayor Pete Buttigieg (21%) and Senator Elizabeth Warren (18%). Other recent polls have shown Biden polling as low as fourth within that top tier, but his support nationally and in some other early states remains strong.
Biden has made electability a central part of his message. During the Liberty and Justice Celebration in Iowa earlier this month, supporters were encouraged to chant "beat him like a drum," repeating a refrain Biden often says on the campaign trail about how he'll take down President Trump.
It's an argument supported by a fair amount of data. Biden repeatedly outpolled Mr. Trump in head-to-head matchups, including in pivotal states like Michigan and Pennsylvania. And a clear majority of Democratic voters say the ability to beat Mr. Trump is the single most important attribute a candidate can possess.
"I think he has a better chance of beating Trump in the Electoral College, which is the number one priority," said Ames voter Rose Caraway, a 38-year-old assistant professor at Iowa State.
But Biden's electability argument doesn't resonate with everyone. At a Biden event before the Liberty and Justice Celebration, 60-year-old Jo Taylor from West Des Moines said she was planning to caucus for Biden, but was also considering Buttigieg. Two weeks later, she now says she would caucus for Buttigieg, citing his performance that night and coming to view him as an electable candidate as well.
"It's still kind of a toss up," Taylor said, but added that she "might be swinging a little more towards Pete."
Making the case about electability puts significant pressure on Biden to have a strong showing in Iowa because it raises expectations, top Democrats say.
"When you're making the argument that the reason why people pick you is because you're a winner, it's important to win," said Iowa Democratic strategist Jeff Link.
Link described Biden as "incredibly resilient" so far in the campaign due to the electability issue, but added that if Biden doesn't win Iowa, it will be important for him to finish a "very close second." However, many of the Democrats interviewed for this story expressed concerns about Biden's ability to win or finish top three in the caucuses.
"If he's not in the top three it's over," a top Iowa Democrat said, who added the former vice president doesn't have the "intensity of support" that other candidates have shown.
Some Democratic leaders and officials cited other hurdles for Biden, such as his struggles with fundraising compared to other top candidates, issues with his campaign's organizing ability, and "lackluster" performances from Biden at campaign stops in Iowa.
Woodard and other Democrats said Biden has faced some trouble from Buttigieg presenting himself as the moderate alternative. Woodard also believes the former vice president should have visited smaller towns with more retail political stops and held more town halls earlier in the cycle.
"People like to be courted," in a state like Iowa, he said.
Jesse Harris, Biden's senior Iowa adviser, said the campaign is looking to get Biden in front of as many Iowans as possible.
According to a CBS News analysis, Biden has made 13 trips to Iowa, spending 27 days here and holding 52 campaign events across 28 of the state's 99 counties. But Biden has spent less time and held fewer campaign events than Buttigieg, Warren and Sanders, although he entered the race later than those rivals. The Biden campaign says it is planning to ramp up Biden's visits to Iowa with Caucus Day less than three months away.
Nate Gruber, the vice chair of Black Hawk County Democrats, said "it feels like a major disappointment" that Biden hasn't capitalized on his name recognition. He added that if the caucuses were held today, Biden would likely finish third behind Warren and Buttigieg.
"There is a fire going, but it is controllable," Gruber said. "It's at that point where if you don't do something it is going to get bigger."
While several Democratic leaders and officials echoed that the campaign is "in trouble," many acknowledged that Biden has been able to hold on to his initial supporters. Others pointed to the success of more moderate candidates in previous cycles, such John Kerry, as reasons for optimism. Kerry had trailed more left-leaning candidates for much of the 2004 Democratic primary, but ultimately won the Iowa caucuses and the Democratic nomination.
A Biden campaign official highlighted the former vice president's consistent strength in the polls against Mr. Trump in general election battleground states. Woodard said Democrats' "vitriol" toward the president could cause many people to take a close look at who's best suited to win a general election, something that could help Biden.
A Des Moines Register/CNN poll released on Saturday found that 63% of likely Democratic caucus goers said they cared more about finding a candidate who has a strong chance of beating Mr. Trump compared to 32% who said they prefer a candidate who shares their position on issues. Most respondents – 52% – said they were almost certain or fairly confident that Biden could beat Mr. Trump, while 46% said the same of Warren and Buttigieg, and only 40% were confident that Sanders could win a general election.
"I think the vast majority of caucus goers are going to say, 'can this person beat Trump? And is this person the most likely to beat Trump?'" Woodard said. "If they can just pound that message home and I think be a little bit more blatant with it in how they're saying it to caucus goers, I think they have a good shot."
In an attempt to reach a wider group of voters, Biden's team in Iowa is targeting not just previous caucus-goers and Democrats, but also independents and Republicans. A Biden campaign offical argued that, for independents and moderate Republicans who dislike the president, "the profile of a candidate like Joe Biden is probably more appealing to you than some of the harder line candidates who are out there."
While the president remains popular among the party rank-and-file, polls and elections have indicated a level of Trump fatigue among some Republican voters, particularly in suburban districts that were once GOP strongholds.
"The man that I thought Trump was when I voted for him is not who he is," said Dubuque voter Cathy Mauk Dickens, 57. She now said she is supporting Biden.
The Biden team has one of the largest organizations on the ground in Iowa. The campaign has also recruited and locked in precinct captains in all 99 counties, who will try to persuade people to support Biden across Iowa during the caucuses. That's a critical piece of success in Iowa and a major organizational challenge for every presidential campaign.
Jesse Harris also pointed to an "aggressive" voter outreach program that is looking to specifically target veterans, Catholics, labor groups and African Americans.
At the same time, Biden's national campaign has downplayed the need to win Iowa on recent calls with reporters. In an interview with a local television reporter in Iowa last week, Biden said he doesn't believe that he has to win the caucuses, but needs to do well in the state.
"If it ends up being statistically close for two, three candidates, then everybody's in it," Biden said. "You can't get blown out in Iowa and go on."
While Harris stressed the Biden team wants to be competitive in Iowa and win the caucuses, he also said there are multiple paths to the nomination for Biden even if he doesn't win Iowa.
"I feel good that we have a national campaign that is thinking broadly about how we can get the number of delegates to win the nomination regardless of how each state kind of shakes out," Harris said. "It gives me reassurance that, you know, we have good people who are thinking about the strategy and not kind of putting all their eggs in one basket."
Biden backers often note that the former vice president has strong support among African Americans, a demographic that will prove increasingly important once Iowa and New Hampshire, which are both overwhelmingly white, are out of the way.
Others, however, note that candidates who win the earliest contests gain a great deal of momentum and tend to keep winning. Since 1976, all but two Democratic nominees have won the Iowa Caucuses.
"Momentum is a real thing," says former Hillary Clinton campaign manager and CBS News contributor Robby Mook.
"Momentum gets you money to do more advertising. Momentum gets you a lot of positive media coverage. And we've seen, in many cases, a direct correlation this year between the amount of coverage people are getting on the news and their performance in the polls."
LaCrai Mitchell and Bo Erickson contributed reporting to this story