© Win McNamee/Getty Images Pete Buttigieg, Andrew Yang, and Beto O'Rourke.

South Bend, Indiana, Mayor Pete Buttigieg's fellow Democratic presidential candidates find the 37-year-old and his mercurial rise to be, well, kind of annoying, The New York Times reports.

That's not unexpected, as former President Barack Obama's chief strategist David Axelrod pointed out. "It is a natural thing when a young candidate comes along and has success for other candidates who feel like they've toiled in the vineyards to resent it," he said.

Sen. Amy Klobuchar (D-Minn.), for example, reportedly became "extremely agitated" at the mere mention of Buttigieg's name during a conversation with fellow candidate Sen. Cory Booker (D-N.J.) in the Senate chamber over the summer. But it turns out that it was former Rep. Beto O'Rourke (D-Texas) who may have been most rankled by Buttigieg's emergence, per the Times. O'Rourke, who dropped out of the race last week, was another relatively young and inexperienced candidate, but he failed to reel in the support that the Indiana mayor has, both in terms of polling and donations.

One O'Rouke aide told the Times that he viewed Buttigieg as a "human weather vane" that represented the worst of politics. Stranger things have happened, but it doesn't sound like Buttigieg can expect an endorsement from O'Rourke anytime soon. Read more at The New York Times.