(Bastien Inzaurralde/The Washington Post)

Donald Trump’s Cabinet nominees, in their first round of confirmation hearings on Capitol Hill, have one after another contradicted the president-elect on key issues, promising to trim back or disregard some of the signature promises on which he campaigned.

A fresh set of examples came Thursday, the third day of hearings.

Retired Marine Corps Gen. James Mattis, Trump’s nominee to be defense secretary, told the Senate Armed Services Committee that the United States must honor the “imperfect ­arms-control agreement” with Iran that Trump has vowed to dismantle because “when America gives her word, we have to live up to it and work with our allies.”

He also took a more adversarial stance than Trump has toward Russian President Vladi­mir Putin and cited Moscow as one of the nation’s top threats.

“I’ve never found a better guide for the way ahead than studying the histories. Since [the 1945 meeting of world powers at] Yalta, we have a long list of times we’ve tried to engage positively with Russia. We have a relatively short list of successes in that regard,” Mattis said. “I think right now, the most important thing is that we recognize the reality of what we deal with [in] Mr. Putin and we recognize that he is trying to break the North Atlantic alliance.”

(Sarah Parnass/The Washington Post)

At a witness table in another Senate hearing room, Rep. Mike Pompeo (R-Kan.), whom Trump picked to head the CIA, assured the Intelligence Committee that he would “absolutely not” use brutal interrogation tactics on terrorism suspects in contravention of the law, even if ordered to do so by a president who campaigned on a promise to reinstate the use of such measures.

Trump indicated in a tweet Friday morning that he is unconcerned about the contradictions. “All of my Cabinet nominee are looking good and doing a great job,” Trump wrote. “I want them to be themselves and express their own thoughts, not mine!”

The discordant notes that Cabinet nominees have struck as they have been questioned by senators suggest that a reality check may lie ahead for Trump.

It may be that the grandiosity and disregard for convention that got Trump elected were inevitably bound for a collision with the practical and legal limitations of governing.

“His rhetoric was so far outside the boundaries — in some instances of reality, and in some instances, of the laws of the nation, and in other issues, outside the boundaries of pass-fail issues for some of these nominees,” said Republican strategist Steve Schmidt, who as an aide to President George W. Bush oversaw the confirmation process for the Supreme Court nominations of Samuel A. Alito Jr. and John G. Roberts Jr.

The American system of government places “extraordinary constraints” on even a president’s power, Schmidt said. “You’re seeing the reality-show aspects of campaigning bending to the reality of governance.”

But others say that Trump is such a singular figure, whose fervent supporters are convinced that he can topple the established order in Washington, that it is impossible to predict how things will play out once he has been inaugurated.

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“We are in such uncharted territory with this guy,” said Elaine Kamarck, director of the Brookings Institution’s Center for Effective Public Management. “The interesting thing will be, does Trump pay attention to what his government does?”

The comments by Mattis and Pompeo on Thursday continued a pattern set in the first two days of hearings.

On Tuesday, retired Marine Corps Gen. John Kelly, nominated to head the Department of Homeland Security, played down the significance of Trump’s promise to build a wall on the U.S.-Mexico border, saying that “a physical barrier in and of itself will not do the job.”

And Kelly, too, disavowed torture, saying, “I don’t think we should ever come close to crossing a line that is beyond what we as Americans would expect to follow in terms of interrogation techniques.”

In 2009, President Obama signed an executive order that bars the CIA from using interrogation methods beyond those permitted by the U.S. Army Field Manual. That excludes such measures as waterboarding. In 2015, that policy was written into law.

Trump, on the other hand, argued during his campaign that “torture works.” He vowed to resume it “immediately” and to come up with “much worse.”

On Wednesday, secretary of state-designate Rex Tillerson contradicted the president-elect’s repeated suggestions that climate change is a hoax and said it is important for this country to “maintain its seat at the table on the conversations around how to address the threats of climate change, which do require a global response.”

As a candidate, Trump had said he would withdraw the United States from a 2015 international accord to reduce ­greenhouse gas emissions, although he has since softened that stance and said he is keeping “an open mind to it.”

That Trump’s nominees would air their disagreements with the president-elect at their confirmation hearings is “extraordinarily unusual,” Kamarck said. “The first thing a president and a transition team does is make sure the president and his Cabinet are on the same page.”

But it may be that they have not yet even discussed their differences.

Among the startling turns in the confirmation hearings has been the revelation by some of Trump’s nominees that they have not had detailed conversations with the president-elect about critical issues that will fall within their portfolios.

Tillerson, for example, told the Foreign Relations Committee that he and Trump had discussed foreign policy “in a broad construct and in terms of the principles that are going to guide that.”

“I would have thought that Russia would be at the very top of that, considering all the actions that have taken place,” Sen. Robert Menendez (D-N.J.) said. “Did that not happen?”

“That has not occurred yet, Senator,” Tillerson replied.

Kelly made a similar comment when he was asked about the fate of hundreds of thousands of undocumented immigrants who have applied for protection from deportation under the Obama administration’s Deferred Action for Childhood Arrivals executive action. In his campaign, Trump vowed to “immediately terminate” the program.

“The entire development of immigration policy is ongoing right now in terms of the upcoming administration. I have not been involved in those discussions,” said Kelly, who is slated to head a sprawling department that includes U.S. Immigration and Customs Enforcement.

One question is whether his appointees will persuade Trump to moderate some of the strident positions that he took during his presidential campaign.

He has already indicated that they have influenced his thinking in some areas.

During an interview with the New York Times shortly after his election, for instance, Trump said that Mattis had made the case that “a pack of cigarettes and a couple of beers” were more effective in getting information from terrorism suspects than waterboarding and similarly controversial techniques.

“I was very impressed by that answer,” Trump said.

Another unknown, however, is how the Cabinet nominees’ views will mesh with those of senior members of Trump’s White House staff, who do not undergo confirmation by the Senate.

Tillerson, for example, said under questioning by the Foreign Relations Committee that supporting human rights globally is “without question” in the long-term national security interests of the United States.

But at a forum a day earlier at the United States Institute of Peace, K.T. McFarland, who will be Trump’s deputy national security adviser, contended that Trump will take foreign policy in a less-idealistic direction.

“The mistake that we make is that we constantly tell other countries how they should think,” McFarland said. “What I’m hoping is that we can start seeing things through their eyes.”

Read more:

As a general, Mattis urged action against Iran. As a defense secretary, he may be a voice of caution.

Placing Russia first among threats, Defense nominee warns of Kremlin attempts to ‘break’ NATO

Tillerson calls U.S. intelligence findings on Russian interference in election ‘troubling’