With President Joe Biden's four-year term almost over, the fates of dozens of ambassadors and other senior national security positions remain pending in the Senate, mostly due to political fights with the rival Republican Party.

"The system is broken," Blinken said in a speech at the Foreign Service Institute, which trains US diplomats, in suburban Washington.

"It's undermining our competitiveness. It's disincentivizing public service," he said.

"Of course, this all feeds our competitors' false narratives of our decline and division. It reinforces their conviction -- their false conviction -- that now is the time to challenge the United States and pursue their revisionist goals," he said.

Blinken said that under his leadership, the State Department has moved to reorganize to address Beijing's growing global clout, including by setting up an internal "China House" to orient US policy.

It also has put resources into key areas of competition between the two powers, including emerging technologies and the South Pacific.

But Blinken said the confirmation process, in which the Senate approves presidential nominees, has set back efforts, citing figures that the average ambassador is awaiting 240 days for approval, compared with 50 days in 2001.

Biden also faulted Congress for uncertainty on budgeting, including the feud over whether to reauthorize funding for the anti-HIV/AIDS initiative PEPFAR.

"We have to find a way to fix this system. We have to do better by our people. We have to do better by our diplomacy," Blinken said.

At the end of Biden's term, around 15 US missions lack ambassadors entirely even though he put forward nominees, according to the running tally by the American Foreign Service Association.

Among them is Cambodia: career diplomat Robert Forden has been in limbo since June 2022, with Republicans attacking him for not preventing Covid testing of US diplomats when he served in the US embassy in Beijing during the pandemic.

Biden also has not put forward new nominees after ambassadors stepped down from prominent postings including Germany and Turkey.

The US ambassador to China, Nicholas Burns, was not nominated until six months into Biden's tenure and he then needed another half-year for Senate confirmation.

The nominee to be ambassador to Libya, career diplomat Jennifer Gavito, recently said she was withdrawing due to the delay, which she said was ceding space in the long-unstable country to Russia and China.