CEDAR RAPIDS, Iowa — As Iowa Democrats begin to coalesce around a few front-running candidates, those who are still struggling to build support in this first-in-the-nation caucus state are facing growing pressure to gain momentum — or quit.

As the clock ticks toward the February 3 caucuses, a culling season has descended on the Democratic field. The candidates outside of the top tier are taking steps to preserve resources, redeploy staff and place their fates in the hands of Iowa voters, sacrificing the national organizations they had hoped to build in favor of a longer-odds bet on breaking out in a single state where voters have a reputation for carefully considering their choices.

"That's the job Iowa does, it winnows the field," said David Yepsen, the veteran commentator who hosts a weekly political affairs show on Iowa Public Television.

"To win, we're going to need a nominee on that stage with Donald Trump who has the ability to go toe to toe with Donald Trump and Iowa — you're looking at her," Harris said Friday.

Carter finished well ahead of every other candidate who ran in the 1976 caucuses, though he only managed a second-place showing — to the uncommitted delegates who could not settle on a candidate.

The most recent New York Times/Siena College poll of Iowa voters showed those top contenders in a tight contest for first place, with Warren at the top. Together, the candidates outside the top four drew a combined 18 percent — good enough to tie Buttigieg for third place.

The decisions to shed staff and focus on Iowa are a reflection of the dwindling number of opportunities any candidate has to make a major impression on voters and leap into the top tier.

On Friday, at the Iowa Democratic Party's analogous Liberty and Justice Celebration , several candidates reached for the lofty rhetorical zeniths Obama achieved then. None moved the crowd of about 12,000 party activists and donors in the same way Obama brought down the house a dozen years ago.

For months, the pundit class within the Democratic Party has complained of an overly bloated field of candidates, one that has prevented the party from coalescing around a few choices who represent the various factions of the party. Now, voters seem to be taking the same attitude.

"There is a feeling that you'll find from caucus-goers that there are good people [in the field] but there are too many of them," Yepsen said. "The field's too crowded."