A new poll released Saturday has former Vice President Joe Biden at the top in Iowa of Democrats competing in the state's caucus, the first contest of the 2020 election. Only four other candidates commanded more than 2% in the poll.

According to a new Des Moines Register/CNN/Mediacom poll released Saturday night, Biden is the top choice for 24% of likely Democratic caucus participants, followed by Sen. Bernie Sanders of Vermont at 16%, Sen. Elizabeth Warren of Massachusetts at 15% and South Bend, Indiana, Mayor Pete Buttigieg at 14%.

California Sen. Kamala Harris rounded out the top five at 7%. Sen. Amy Klobuchar of Minnesota and former Rep. Beto O'Rourke of Texas both polled at 2%. All other candidates polled at 1% or below.

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The poll comes as 19 candidates will descend on Cedar Rapids, Iowa, on Sunday for the state's Democratic Party's Hall of Fame Celebration. Biden will not attend due to a family commitment, but will be in Iowa on Tuesday and Wednesday.

At the event, candidates will have a chance to speak directly to 1,400 Democratic activists, as well as over 100 members of the media. The event also gives campaigns a chance to show off their organizing strength and presence in the state.

The candidates will only have five minutes each to give their speeches, but former Democratic operative Grant Woodard, who worked on Hillary Clinton's 2008 Iowa campaign, told CBS News the event can make a difference.

"It might give a candidate an audience of some folks that wouldn't have ordinarily gone to one of their events," Woodard said. "Five minutes is a short amount of time, but you can really make a statement in that time and maybe have an opportunity to have more people consider actually showing up to your events."

For the first time, the poll factors in the new virtual caucuses, which will account for 10 percent of the results. Twenty-eight percent of respondents said they are likely to participate in the caucuses virtually. That makes it different from previous versions of the poll, and The Des Moines Register notes it is not directly comparable to past Des Moines Register/CNN/Mediacom polls, which have also had Biden and Sanders at the top.

In an early March poll before Biden entered the race, he led the way with 27% of likely Democratic caucus participants saying he was their top choice. He was followed by Sanders at 25%, Warren at 9%, Harris at 7%, O'Rourke at 5% and Buttigieg at 1%.

Among those who say they plan to participate in virtual caucuses, 33% say Biden is their top choice, followed by 14% for Warren. Harris and Sanders were both the top choice among 10% of expected virtual caucus goers.

Woodard says the virtual caucuses will add a new wrinkle, but the campaigns can't forget about the in-person participants.

"Obviously campaigns have to prepare for it, but if I was managing a campaign my first priority would always be getting people actually there," Woodard said. "Then you can at least feel like you can control that and actually see the numbers of people."

The caucuses are not until February, and the poll found there are eight candidates who are either one of the top two choices or actively being considered by at least 30% of caucus goers who plan to participate in person. Woodard said the next few months will be critical for how campaigns strategize in Iowa.

"Campaigns are going to have to make a decision on what type of resources they really want to put in here," Woodard said. "I think you might see some step up their Iowa game, you might have some that just totally don't participate other than show up to cattle calls."

Outside of the race, the poll found that likely Iowa Democratic caucus participants are divided on impeachment. Nearly half, 48%, who plan to attend the caucuses in person say Congress should continue to investigate President Trump, but not move ahead with formal impeachment proceedings. Forty-two percent said they support moving ahead with impeachment.

The poll was conducted between June 2-5 with a random sampling of 600 likely Democratic caucus participants reached on landlines or cell phones. It has a margin of error of 4.0 percentage points for combined preference, 4.7 percentage points for in-person attendees and 7.6 percentage points for virtual participants.