WASHINGTON ― President-elect Donald Trump will nominate John Bolton to be the nation’s No. 2 diplomat, handling day-to-day operations at the State Department, according to NBC’s Andrea Mitchell and confirmed to HuffPost by a source close to the transition.

Bolton, who had been on Trump’s short list for secretary of state at one point, is among the most hawkish members of the Republican foreign policy community, a bellicose enemy of Russia and Iran.

He is a former acting U.S. ambassador to the United Nations, but served less than two years, as Democrats banded together to block his long-term appointment. His time at the U.N. was marked by a rapid uptick in anti-American sentiment among the global diplomatic community. Bolton remains one of the most disliked foreign policy operators on the world stage.

Trump’s search for State Department leadership has been particularly dramatic. Former New York Mayor Rudy Giuliani was in the running, and then he bowed out on Friday. The GOP’s 2012 presidential nominee, Mitt Romney, was also considered. But media outlets reported Saturday that Trump had settled on Exxon Mobil CEO Rex Tillerson for the top State Department job.

Even as the second in command at State, Bolton is an aggressive selection from Trump, shattering the president-elect’s pledge to work peacefully with other countries. Bolton, who has called for the bombing of Iran, held high-level roles in three different Republican administrations between 1998 and 2006. He is now a senior fellow at the American Enterprise Institute, a conservative think tank whose vice president has described Trump as “an idiot.”

He would be reporting to a commander-in-chief who appears to espouse a worldview diametrically opposed to his own. Bolton has repeatedly slammed President Barack Obama for his willingness to engage in limited cooperation with Russian President Vladimir Putin in Syria and Iran.

“While Mr. Obama sleepwalks, Mr. Putin is ardently pursuing Russia’s Middle East objectives,” Bolton wrote in a 2013 op-ed that argued against assuming the U.S. has common interests with Russia in Syria.

In 2014, speculating that Russia was responsible for the downing of a Malaysian plane over Ukraine, Bolton told Fox News, “I think we’ve got to begin to treat Russia like the adversary that Putin is currently demonstrating it to be.”

Two years later, Bolton expressed hope that Obama wouldn’t do anything in his final year in office to legitimize Russia’s military efforts in Syria, where U.S. defense officials say Russia is focused on bombing Syrian opposition fighters rather than Islamic State forces. “Until Mr. Obama departs the White House,” Bolton wrote in October 2015, “Washington must not do anything perceived as legitimizing Moscow’s new Latakia air base, or the presence of Russian aircraft and cruise missiles in the skies over the region. The suggestion that we exchange deconfliction codes with Russia is what the French call a fausse bonne idee, a superficially appealing bad idea.”

Trump, a man who has extensive financial ties with Russia, is far more likely than Obama to legitimize Moscow’s military endeavors in the Middle East. He has already broken with the Republican orthodoxy by suggesting that the U.S. abandon its efforts to fight ISIS in Syria and let Russia take over.

“This has happened before. We back a certain side, and that side turns out to be a total catastrophe,” Trump said in September, referring to U.S. support for the opposition groups fighting ISIS and Syrian President Bashar Assad. “Russia likes Assad, seemingly, a lot — let them worry about ISIS. Let them fight it out.”

In a phone conversation last month, Trump and Putin committed to working to normalize relations, a Kremlin readout of the call said. The current relationship, the two leaders agreed, is “extremely unsatisfactory.”

Yet Trump listed Bolton as one of his “go-to” experts on national security issues during a “Meet the Press” interview in August. “He’s, you know, a tough cookie, knows what he’s talking about,” Trump said.

It was a curious comment from a man who had spent the previous several months (falsely) boasting that he was opposed to the 2003 U.S. invasion of Iraq and hitting his opponent for her vote in support of the war. Bolton was in favor of invading Iraq as early as 1998. In the lead-up to the invasion, Bolton, then under secretary of state for arms control, peddled false information about Saddam Hussein’s weapons of mass destruction program. Even after it became clear that the Iraqi dictator did not possess such weapons, Bolton maintained that the war was a good idea.

On the other hand, Bolton has a major supporter in Robert Mercer, a hedge fund billionaire who provided the lion’s share of the financial backing for Trump’s candidacy. The largest donor to Bolton’s super PAC over the years has been the Mercer family. And in 2014, Trump gave $5,000 to the super PAC.