Press secretary Karine Jean-Pierre broke down in tears at Wednesday's White House press briefing even as she secretly blocked a rival from speaking at the last media availability of President Joe Biden's administration.

She spent several minutes at the briefing thanking her colleagues, her family and the president, noting this was the administration’s 537th press briefing and her 306th briefing. 

She said she hoped her visible, public role was an 'inspiration to many young girls out there.'

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.

The White House on Monday said Iran was in some cases "actively facilitating" rocket and drone attacks by Iranian-backed proxy groups on U.S. military bases in Iraq and Syria, and President Biden has directed the Department of Defense to brace for more and respond appropriately.

White House spokesman John Kirby said there had been an uptick in such attacks over the last week, and especially over the last few days, but the U.S. would not allow its interests in the region to "go unchallenged."

Kremlin spokesperson Dmitry Peskov was “just lying” when he accused Washington of coordinating drone attacks on Moscow, National Security Council spokesperson John Kirby said Thursday.

“I can assure you that there was no involvement by the United States. Whatever it was, it didn’t involve us,” Kirby said on MSNBC when asked about Peskov’s comments. “We had nothing to do with it. Peskov is just lying there, pure and simple.” On CNN soon after, he called it a “ludicrous claim.”

The Biden administration has “significant concerns” in some cases about China’s behavior when it comes to abiding by the international rules of the road, NSC spokesman John Kirby said Tuesday.

Chinese President Xi Jinping and Russian President Vladimir Putin are meeting on Tuesday in Moscow.