While President Biden's pick for Ambassador to Australia is widely rumoured to be Caroline Kennedy, she has not yet been officially nominated. Of the 80 ambassadors nominated by Biden in his first year, only 16 per cent have been confirmed. This is the inverse of President Trump who had 77 per cent of the ambassadors he nominated in his first year confirmed by the Senate.
Ambassadorial nominees require unanimous support of the Senate, which is not usually an issue. However, Senator Ted Cruz has used this lever to force action against the Russian pipeline through Ukraine. This stalemate led Secretary of State Antony Blinken to make an unprecedented appeal to the Senate to move forward and clear the backlog. At this stage, it is unlikely Australia will have a new US ambassador appointed any time soon.
Ambassadorial nominations vs confirmations in first year