WASHINGTON — In May, just weeks after becoming secretary of state, Mike Pompeo returned to Capitol Hill for defiant and surprisingly heated exchanges about diplomacy with his former Democratic colleagues.
“I’ll take a back seat to no one with respect to caring about and protecting the people,” he said of diplomatic security in one blistering answer during a hearing in the House, where he had served for six years as a Republican congressman from Kansas. Before the Senate, he dismissed another question from a Democrat as “bizarre” and “outrageous.”
At the time, Mr. Pompeo could afford to dismiss minority Democrats who had little to no sway over the State Department. That will change in January, when Democrats will take over the House and have subpoena and budgetary powers on the Foreign Affairs and Appropriations Committees — both of which serve as a check on the State Department.
Even in the Senate, where Republicans retain control, Democrats on the Foreign Relations Committee can continue to hold up nominations at the State Department, which is struggling to fill its ambassador ranks and other senior diplomatic posts.
“I hope we can work collaboratively to get the answers the American people are seeking,” Representative Eliot L. Engel, a New York Democrat who is in line to be the next House Foreign Affairs chairman, said in a statement.
Mr. Engel said he intended “to make sure our diplomats can do their work free from partisan abuse.”
The newly treacherous political environment comes as Mr. Pompeo’s honeymoon as the nation’s chief diplomat has ended within the State Department, and the administration’s foreign policy strategies are under strain around the world.
President Trump has made clear he supports Mr. Pompeo’s approach. “Mike Pompeo has fit in so beautifully. He’s done an incredible job,” Mr. Trump said in a postelection news conference on Wednesday.
Democrats on the House Foreign Affairs Committee said they intended to launch a stream of investigations once they were in control.
They want to look at whether Mr. Trump’s international business interests have affected American foreign policy; what was said at the July summit meeting in Helsinki between Mr. Trump and President Vladimir V. Putin of Russia; and if State Department political appointees have used loyalty tests to screen career diplomats for choice assignments.
Probing the administration’s strategies in Yemen, Afghanistan and North Korea are also priorities for Democrats, who said Mr. Pompeo and his aides had done little to answer their queries — a complaint that even Republicans quietly echo.
In one example, Mr. Pompeo promised during his testimony in May to expeditiously appoint envoys to monitor anti-Semitism and L.G.B.T. rights. “You have my word we’ll move on them,” he said. The appointments are still pending.
In the Senate, the new chairman of the Foreign Relations Committee is expected to be Senator Jim Risch, a little-known Idaho Republican who aligns closely with Mr. Pompeo’s traditional anti-Russia, anti-Iran conservatism. But in dealings with North Korea, Mr. Risch has quietly secured assurances that a senatorial observer be included in negotiations heading toward a treaty — ensuring a check on the sensitive talks.
Beyond Washington, Mr. Pompeo’s challenges have also been mounting.
A canceled meeting in New York last week between Mr. Pompeo and North Korea’s leading nuclear weapons negotiator was the latest sign that the talks are at an impasse, even as Pyongyang adds to its nuclear and ballistic missile arsenals.
Mr. Trump’s troop surge to resolve the 17-year war in Afghanistan appears headed for defeat or retreat. The administration’s long-gestating peace plan for Israel and the Palestinians faces severe hurdles, and President Bashar al-Assad of Syria has solidified his hold over his shattered country. Venezuela continues to slide into anarchy, relations with Russia are worsening, governments in Pakistan, Turkey and across Eastern Europe are increasingly anti-democratic, and China’s influence in Latin America, Africa, South Asia and elsewhere continues to blossom.
Also troubling, once reliable allies are edging away from the United States — or becoming liabilities.
President Emmanuel Macron of France called last week for the creation of a European army amid a fraying NATO alliance with the United States. Tokyo and Seoul have both launched charm offensives with Beijing to hedge against an unpredictable Washington. And Saudi Arabia’s lethal tactics in Turkey and Yemen have made it an object of international opprobrium.
Mr. Pompeo may have just days to rehabilitate Saudi Arabia’s reputation before Congress considers serious penalties against Riyadh. Mr. Pompeo’s call late last month for a cease-fire in Yemen, where a humanitarian disaster is intensifying, has so far been ignored.
And then there is Iran. Early this month, Mr. Pompeo announced the re-imposition of the last set of sanctions that were lifted under the 2015 nuclear accord. Anti-Iran hawks who had eagerly awaited the moment complained that the administration did not go far enough, and it remained unclear if the rest of the world would heed the United States’ demands to reject Iranian exports.
Mr. Pompeo’s handling of these myriad challenges has gotten mixed reviews in an administration dominated by a mercurial president whose blistering tweets overshadow, and often undermine, what the State Department seeks to accomplish.
The primary tools Mr. Trump has employed to shape world events are tariffs and sanctions, but Mr. Pompeo has control over neither.
Negotiations over North Korea, Afghanistan and Syria are among the foreign policy priorities that Mr. Pompeo leads, but so far with few successes to show.
Morale at the State Department has recovered since the tenure of Rex W. Tillerson, the former secretary of state — but just barely.
“Most career diplomats are proud idealists who want to advance America’s interests by making the world a better place,” said Nancy McEldowney, a former ambassador who retired last year after a 30-year career as a Foreign Service officer. “Many of them are deeply ashamed of the bullying, transactional and in many cases amoral policies of this administration.”
Mr. Pompeo is widely seen as close to the president. But the president gave his chief diplomat an impossible task when he sent Mr. Pompeo to confront Riyadh in the wake of last month’s killing of Jamal Khashoggi, the Saudi dissident, in the Saudi Consulate in Istanbul.
Pictures of Mr. Pompeo smiling and laughing with Crown Prince Mohammed bin Salman of Saudi Arabia drew widespread condemnation and marked the lowest point of his State Department tenure.
“The biggest challenge for him is that he has become Trump’s firefighter,” said James J. Carafano, a fellow at the Heritage Foundation and a member of Mr. Trump’s presidential transition team. “Sending him to meet the Saudis and Turks accomplished nothing, and it wasn’t the right mission for him.”
After months of relative quiet at Foggy Bottom, Mr. Pompeo began to emerge in recent weeks, giving a host of interviews in which he firmly stuck to administration talking points.
“Securing our southern border, enforcing American sovereignty is an enormous national security issue,” Mr. Pompeo told Sean Hannity, the Fox News host, on Nov. 2. “It’s why as secretary of state, I’ve been very involved in these discussions” about the migrant caravans moving through Mexico.
But he has also held off-the-record talks at think tanks and academic centers, where he has been described as deeply knowledgeable and far from doctrinaire.
In public, Mr. Pompeo expresses optimism about talks with Pyongyang. In private, he is far less sanguine, according to those who have spoken with him.
Analysts see that divide as stemming from the fundamental difficulty of his job — managing a president whose pronouncements often diverge substantially from basic facts. As recently as Wednesday, Mr. Trump said talks with North Korea were “going fine.”
Mr. Pompeo “reacts to the president’s momentary impulses but has no visible or articulated sense of priorities, sequencing or underlying strategy,” said Eliot A. Cohen, a military historian who worked for President George W. Bush. “But that’s probably not his fault.”