They share a podium — and a mutual frustration. White House press secretary Karine Jean-Pierre and the National Security Council's John Kirby frequently split the podium at media briefings, but behind the scenes their relationship is fraught with tension, White House sources tell Axios.

Why it matters: As President Biden heads into a tough re-election campaign, his top-ranking spokespeople are at odds while navigating a situation in which there's one press secretary in name but two in practice — one for domestic policy, the other for foreign policy.

Zoom in: Some of the tension stems from how much time each gets at the podium each day.

• Kirby — a Biden favorite who has become the public face of the administration's response to the Israel-Hamas war — has told people he'd like to be White House press secretary one day.
• Jean-Pierre has told people she plans to stay in the job through the election and beyond if Biden wants her — and that he has asked her not to leave.
• A White House official told Axios that Kirby never volunteers that he would like to be press secretary.
• Jean-Pierre and Kirby have split the podium in the White House pressroom more frequently since the Israel-Hamas war began in October — aggravating tensions that began in the spring of 2022, when Jen Psaki departed as press secretary, current and former Biden officials said.

Between the lines: They both keep appearing at the podium together for one reason: Biden likes it.

• Kirby has become more influential publicly and behind the scenes as he has developed a close relationship with the president.
• Biden frequently asks for Kirby to personally brief him. Senior adviser Anita Dunn recently had Kirby start traveling on Air Force One for domestic trips, not just international ones.
• In the more than 30 press briefings and gaggles since Hamas attacked Israel on Oct. 7, Jean-Pierre has briefed reporters solo just once — during a gaggle on Air Force One.
• Kirby has accompanied her at every other briefing she has conducted except for three, when she was joined by National Security Adviser Jake Sullivan. (Sullivan joined once because Kirby was ill, according to two people familiar with the matter.)

Jean-Pierre still runs the press briefings and selects which reporters ask Kirby questions, rather than letting him choose.

• That's standard procedure for most briefing room guests. But Kirby is there often, and has expressed frustration that it applies to him. Some White House aides see the practice as a sign of Jean-Pierre being insecure.
• The aides note that Sullivan calls on reporters himself when he attends the briefing — a practice that began during Psaki's tenure.

What they're saying: A White House official who works closely with Jean-Pierre and Kirby disputed the notion that there is tension between the two.

• " I don't recognize this description of their relationship at all. The truth is the opposite — they talk all the time and have a collegial and collaborative rapport," the official said.

The intrigue: But several other White House sources say Jean-Pierre was wary of Kirby from the beginning.

• When Biden offered Jean-Pierre the press secretary job in 2022, he awkwardly added that Kirby also would be joining and that they'd be a team, Jean-Pierre told people afterward.
• Jean-Pierre left the meeting with Biden upset and confused about whether she actually had the job and what Kirby's role would be, according to three people familiar with her comments at the time.
• A White House official told Axios that it's overwhelming — in a good way — to be offered the prestigious job, and that Jean-Pierre was not upset or confused.
• Ron Klain, then the White House chief of staff, met with Jean-Pierre to try to smooth things over and reassure her that she was the press secretary. He and Dunn then worked to find an agreeable arrangement. (Klain did not respond to a request for comment.)

National Security Council leaders then were told, to their surprise, that Kirby — the two-time Pentagon press secretary and State Department press secretary — would join their team.

• After haggling over what Kirby's role would be, the White House and the NSC settled on the title of "coordinator for strategic communications."
• Kirby, however, doesn't supervise or report to the NSC communications director. His role is more focused on public communications than coordinating messaging across the administration.

Jean-Pierre's relationship with her principal deputy, Olivia Dalton, also has been bumpy. Dalton voiced frustrations during her first year, when she didn't brief from the podium despite several months of practice sessions.

• Dalton has conducted more gaggles on Air Force One recently, but has briefed reporters from the podium just once — last June.
• A White House aide who works closely with Jean-Pierre and Dalton told Axios: "They have been friends for over a decade and have a strong relationship."

Zoom out: Many current and former Biden officials argue that Klain and Dunn are responsible for the current tension, saying the unusual setup is unfair to both Jean-Pierre and Kirby.

• Before she became press secretary, Jean-Pierre didn't deal with many tough stories in the press, and wasn't as experienced as Kirby or Psaki in combative briefing environments.
• Jean-Pierre's defenders say the arrangement undermined her from the beginning and made a difficult job harder. Some Black Democrats in the administration and on Capitol Hill say the situation was insulting because it suggested that the first Black press secretary to represent the president needed supervision.
• Some current and former Biden aides have been frustrated by some flubs, such as when Jean-Pierre answered a question about antisemitism by talking about Islamophobia. She later said she misheard the question.
• Other current and former Biden officials say that both Jean-Pierre and Kirby should put aside any frustrations and embrace the arrangement, given the chaotic world and the critical election ahead.

Editor's note: This story was updated with an additional comment from a White House source.