David Axelrod warned that Pete Buttigieg's public opining about the 2020 Democratic primary is "unhelpful" to the South Bend, Indiana, mayor and a "campaign strategist's nightmare."

"The campaign strategist’s nightmare: When the candidate goes all pundit in an interview. Unhelpful," tweeted the chief strategist for President Barack Obama's campaigns on Saturday. Linking to a Newsweek article, Axelrod added the mayor's punditry was "Honest but unnecessary. All part of learning the rules of a game in which candor can sound like hubris."

Honest but unnecessary. All part of learning the rules of a game in which candor can sound like hubris. — David Axelrod (@davidaxelrod) November 2, 2019

The 37-year-old Buttigieg recently told John Heilemann of Showtime's The Circus that he foresees the 2020 Democratic primary shaping up to be "a two-way" between himself and Massachusetts Sen. Elizabeth Warren. "It's early to say," he said. "I'm not saying that it is a two-way. ... A world where we're getting somewhere is that world where it's coming down to the two of us."

[Related: 'A modern-day Pharisee': Buttigieg's evangelical brother-in-law urges him to 'repent' of abortion views]

Buttigieg also dismissed the front-runner status of former Vice President Joe Biden, saying, "Either he is the unstoppable front-runner — and we can all go home — or he is not. Anybody who's in this race is pure on the assumption that he's not."

Queue up “Just the Two of Us,” @PeteButtigieg thinks this race is between him and @ewarren.



See the full interview on a new episode of @SHO_TheCircus this Sunday at 8pm on @showtime. pic.twitter.com/FZV0PMTWWq — John Heilemann (@jheil) November 1, 2019

Buttigieg has remained resilient in the polls as others once deemed to be top-tier candidates have fallen away, such as California Sen. Kamala Harris, who is already hemorrhaging staff. Buttigieg seized second place in the latest RealClearPolitics poll of Iowa voters, coming in at 17% behind Warren's 22.3%.

Democratic strategists are already floating the possibility that Buttigieg could end up being the Democratic nominee, with former Clinton staffer Michael Gordon recently telling Newsweek, "You could picture him more going toe-to-toe with Trump. He has a real moral authority in the way he talks, so he's someone ... who could surprise in, like, Iowa."