(CNN) -- Calling attention to a logjam of stalled diplomatic nominations in the Senate, Secretary of State John Kerry said the delay is harming U.S. national security.
In direct public commentary on an issue crossing politics and diplomacy, Kerry called for swift approval of the nominees, many of whom are career diplomats. Some were selected for difficult jobs in global hotspots.
"Make no mistake: Vacancies in so many world capitals send a dangerous message to allies and adversaries alike about America's engagement," Kerry said in an opinion piece for Politico on Tuesday.
"This perception makes it much more difficult to do the nonpartisan work at the heart of U.S. foreign policy — defending the security of our nation, promoting our values and helping our businesses compete to create American jobs back home," he added.
Fifty-three State Department nominees await confirmation. Nearly two thirds are uncontroversial career diplomats who are caught up in a partisan standoff that has nothing to do with them or the jobs they've been tapped to undertake.
Democrats lead the chamber and accuse Republicans of delaying confirmation votes as payback for new rules aimed at making it easier to break Republican filibusters on nominations.
Republicans require separate votes for each nominee, rather than the customary practice of allowing votes on multiple names at once.
White House spokesman Josh Earnest urged Senate Republicans to, "stop playing political games and let these individuals get to work on behalf of the American people."
But Republicans blame the other side.
In an interview with CNN's Jake Tapper, Sen. Rob Portman of Ohio said the GOP has no choice but to take the slow approach.
"The leaderships on the Democratic side of the aisle has chosen, for the first time ever, at least in modern history, to say, 'You know, Republicans are not going to have a voice in these nominees,'" Portman said of the rules change.
Now, Kerry is urging members of both parties to cooperate and act swiftly.
Some 40 countries are awaiting permanent ambassadors, including Qatar and Kuwait, Gulf allies whose cooperation is critical to the fight against extremists in Iraq.
Embassies in Honduras and Guatemala are also waiting for new ambassadors at a time when unaccompanied minors from Central America are surging across the southern border, creating what the White House calls a humanitarian crisis.
And in Africa, nearly a quarter of U.S. missions are awaiting permanent ambassadors. Those include Cameroon and Niger, where the State Department insists the lack of American leadership has hampered efforts to recover hundreds of schoolgirls abducted by the Boko Haram extremist group in neighboring Nigeria this year.
"Ambassadors are there for a reason," Assistant Secretary of State for African Affairs Linda Thomas-Greenfield told CNN. "They speak for the President. They speak for the administration. Not having those voices on the ground has made a difference in our ability to convey the messages we need to convey to these governments."