Secretary of State Mike Pompeo turned the tables on Sen. Bob Menendez (D., N.J.) this week, blaming the New Jersey Democrat for blocking at least a dozen qualified candidates for key diplomatic posts.

Over the last year, Menendez has repeatedly blasted President Trump for jeopardizing U.S. foreign policy by failing to nominate candidates for key foreign policy posts.

Menendez, the ranking Democrat on the Senate Foreign Relations Committee, took the administration to task in a Senate floor speech in March for failing "to nominate critical high-level positions—undersecretaries, assistant secretaries—leaving a void of empowered voices."

He faulted Trump for leaving vacancies at embassies in some of the world's "most troubled regions" including the ambassador to South Korea and the assistant secretary for East Pacific Affairs.

Similarly, in the Middle East, Menendez complained at the time that Trump had failed to appoint ambassadors to "consequential posts" in Saudi Arabia, Egypt, Qatar, Turkey, and Jordan, important players in the war on terror and the Syrian refugee crisis.

"How can we possibly expect to assert American leadership and secure our interests with these posts unfilled, with no empowered individuals at the Department itself?" Menendez asked in the speech.

Menendez continued the same line of criticism this week. While reacting to U.S. Ambassador to the United Nations Nikki Haley's resignation, the New Jersey Democrat argued that the administration's "inability to adequately or appropriately fill key national security positions puts our nation at risk."

The statement angered Pompeo, who tangled with Menendez during his own Senate confirmation process and several times since.

The comments from Menendez, who is locked in tight re-election campaign, are particularly vexing for Pompeo who has repeatedly pledged to fill key posts in the months since his confirmation as a way to help the State Department get its "swagger back.

Pompeo issued a press release Wednesday night that was unusually critical of a sitting senator coming from a secretary of state. In it, he placed the blame for any national security "risk" to the nation squarely "at the feet" of Menendez, who he accused of obstructing with the help of his Senate Democratic colleagues.

"Today, there are more than 60 State Department nominees awaiting confirmation in the United States Senate," he said. "That's more than a quarter of all the senior-level confirmable positions at the Department."

More than a dozen of these "qualified political nominees" are being held up by Senate Democrats because of politics, he said, before pointedly blasting Menendez for his role.

"Yesterday, astonishingly and shamefully, Senator Menendez blamed the administration for a lack of confirmed nominees when he said, ‘This administration's continued inability to adequately or appropriately fill key national security positions puts our nation at risk.'"

"These outstanding candidates remain unconfirmed because Senator Menendez and some of his colleague are using our nominees as a political football. This is unacceptable," he said.

While key senior undersecretary of state positions remain vacant, the administration has worked to appoint or nominate a number of candidates for important positions and ambassadorships. Filling these roles would help Pompeo build out his team and regain control of agency that had been largely rudderless during the first year of Trump's presidency.

There are currently 49 ambassadorial nominees awaiting Senate confirmation. Only one of those is being held up by Senate Republicans: Joseph Macmanus, the nominee to be ambassador to Colombia, who has been criticized for his close ties to former Secretary of State Hillary Clinton and his role in the Benghazi aftermath, among other issues.

Another 104 of the total 188 ambassadorial posts have won Senate confirmation and are in their roles, while Trump has yet to nominate candidates for another 35.

Democrats have pushed back on Pompeo's claim that 65 State Department nominees have been blocked by Democrats, laying some of the blame on Republican leaders, in a memo Menendez penned that became public last week when the frustrations over the nomination backlog spilled out into the public.

Menendez also argued that some of Trump's candidates have questionable qualifications, a point that is perennially made about a portion of every president's ambassador selections because political donors and allies often wind up on the shortlist.

Senate Majority Leader Mitch McConnell (R., Ky.) has yet to wade into the fight, seemingly to avoid further antagonizing his Democratic colleagues in the intensely partisan atmosphere after the national firestorm and confirmation of Brett Kavanaugh to the Supreme Court.

Democrats have the power to derail a nominee simply by having one senator object to move forward to a final vote on the nominee. McConnell could force the issue but doing so consumes valuable time on the Senate floor.

Without unanimous consent, each vote requires 30 hours of debate under Senate rules—which would become unworkable if Democrats insist on such a process for each of the remaining 49 ambassador nominees.

Vulnerable Democrats agreed to confirm 15 judges Thursday, a calculation by Senate Minority Leader Chuck Schumer (D., N.Y.) to consent to the nominations to allow vulnerable Democrats to go back to their states and campaign until Election Day. That agreement with McConnell did not include State Department nominations.

Critics argue that Trump still has yet to nominate a top diplomat in Egypt, Turkey, and Saudi Arabia, where an international dispute over the disappearance of a U.S.-based Saudi journalist is roiling diplomatic waters with one of Washington's closest allies in the region.

Senior U.S. career foreign service officers are continuing to fill the diplomatic vacuum in those countries, which is not ideal in terms of helping Trump promote his own agenda but is also a far cry from leaving the embassies devoid of qualified leadership.

Meanwhile, numerous qualified nominees that appeared to have little to no resistance in the Senate have been waiting months in limbo.

For instance, Kimberly Breier, a Latin America expert who had served as a member of the intelligence community for many years, has been waiting seven months for a Senate confirmation vote to become the assistant secretary of State for Western Hemisphere affairs.

The role would oversee the U.S. response to the humanitarian crisis in Venezuela, U.S. assistance to the flood of refugees in neighboring countries, Colombia's record cocaine production, as well as what many expect will to be Trump's stepped-up response to countering Russian and Chinese involvement in Central and South America.

Despite harsh questioning from Menendez during her June confirmation hearing, the panel agreed to swiftly move her nomination to the floor. However, the nomination has been stalled ever since.