Just days ahead of the Iowa caucuses, 2004 presidential candidate and former DNC chair Howard Dean told ABC's "Powerhouse Politics" podcast that in the final moments, candidates should not totally write-off shifts in support.
Dean, also the former governor of Vermont, said one of the things he's learned in his political career is that often there are "huge momentum shifts in the last three days."
"Iowans are very thoughtful and they’re going to calculate who can win against [President Donald] Trump," Dean told ABC News' Chief White House Correspondent Jon Karl and Political Director Rick Klein. "They’re going to calculate who they like and what message they want to send."
As the candidates tour the Hawkeye State giving their final pitch to voters before Monday, Dean said the caucuses will be a clear sign of each campaign’s ground game -- and how well they have prepared to sway voters once they get in their caucus sites.
"What it does show is how well people can organize," Dean said. "They change their minds all the time. In fact, they change their minds in the caucuses, because this is a big discussion inside a room."
Karl highlighted Dean’s 2004 campaign for the White House and how his momentum changed throughout the cycle, eventually leading to former Sen. John Kerry winning Iowa and going on to receive the Democratic nomination.
"I could feel it slipping away with about three weeks to go. We weren’t sharp," Dean said. "You know, the mood shifted."
Klein asked him about the possibility of a contested Democratic convention come July, where it is possible that one Democrat would not have the number of delegates needed -- 1,991 -- to secure the Democratic nomination.
That scenario would open up the vote to superdelegates, Dean being one of them, who are party leaders free to support any candidate.
Their votes are typically only ceremonial, and this year they would only be permitted to vote for a presidential nominee on a second or subsequent ballot at the convention.
He added, "The last brokered convention was in 1952."
It’s also possible, according to Dean, that the candidate leading in delegates won't secure the nomination.
As for who he is going to vote for, he said he's still undecided.
"What I want is somebody who can win and somebody who will take the Senate with them," Dean said. "I’m going to vote for whoever the hell gets the nomination in the general."
He continued, "And I’m going to work my butt off for them because Trump is a disaster."
As Karl pointed out, the seemingly unified Republican party, coupled with Trump’s reelection war chest and strong economy, could put him in a strong place come November.
Dean didn't deny that possibility -- adding that the turnout of his supporters to events has played a key role in his 2020 campaign.
"The odds of him winning reelection are 50-50. He’s got this loyal fanbase that has terrified the Republicans," Dean said. "It comes down to this: turnout."
He stressed, "If we get to those polls, we’re going to win."