Almost half of Democrats have decided who to vote for in 2020 -- but that may not stick

(CNN)It's more than seven months until the Iowa caucuses and there are nearly two dozen candidates, but 44% of Democratic voters are already saying that they will definitely support their first choice for the nomination, according to the a new CNN poll conducted by SSRS.

The proportion of the Democratic electorate who are feeling confident that they've already picked the right candidate appears to be growing. The new poll showed an 8 percentage point gain in the share of voters who've made up their minds from the April CNN poll, which found 36% of registered Democrats and Democratic-leaning independents had chosen and would definitely support their candidate. Over half (55%) still said they might change their mind, down from 64% in April.
Later this month, 20 candidates will take the stage for the first formal debates of the cycle. There are a record number of Democrats who have declared to run for president in 2020, a gigantic field that has led to many voters struggling to differentiate between them. Even still, 53% of Democrats and Democratic-leaning independents said that the large number of people running for the nomination is a good thing for the party, according to the recent poll.
Supporters of former Vice President Joe Biden and Vermont Sen. Bernie Sanders were the most likely to report that they would definitely support their candidate over other possibilities.
    Forty-three percent of those who said they will definitely support their first choice of candidate plan to vote for Biden, while 29% plan to support Sanders. Further down the line of candidates, 7% said the same for Massachusetts Sen. Elizabeth Warren, 5% for California Sen. Kamala Harris, 3% for South Bend, Indiana, Mayor Pete Buttigieg and 1% for former Texas Rep. Beto O'Rourke.
    For Harris, Warren, Buttiegieg, and O'Rourke, more of their supporters said they may still change their mind than said they will definitely vote for them.
    Democrats and Democratic-leaning independent voters who earn under $50,000 a year, nonwhite Democrats and those without a college degree were the most likely to report that they've already decided on their vote.
    Those who earned over $50,000 a year, college graduates, white Democrats and men were more likely than other groups to think they could still change their mind.
    The share of voters who say they've decided on their vote will almost definitely increase as the election nears.
    Two-thirds of Democrats and Democratic-leaning independents said they had made their choice in late February 2016, as the first month of caucuses and primaries wrapped up.
    But the fact that 44% of Democratic voters say they've already made up their minds this early in the race shouldn't be seen as a rock solid figure that's unlikely to change going forward.
    A similar question, asked throughout 2007, found anywhere between 40-50% of voters said they had made up their mind.
      In March 2007, a CNN poll found 45% who said they will definitely support that candidate in the 2008 election. In October of the same year, that number moved up to 50%. Only a month later, it fell back down to 40%. Meaning, within the span of nine months, there was a 10-percentage point fluctuation in the share of Democratic voters who said they had made up their minds.
      That's not to say that the same thing will happen this year. It is still far off from the actual start of caucus and primary season, and the field is utterly humongous. It's hard to say whether Democrats who are sure of their vote now will feel the same in a year. But at least 44% of them think they will.