In The New Yorker, Jane Mayer writes about Christopher Steele's contribution to uncovering Russiagate:
One subject that Steele is believed to have discussed with Mueller’s investigators is a memo that he wrote in late November, 2016, after his contract with Fusion had ended. This memo, which did not surface publicly with theothers, is shorter than the rest, and is based on one source, described as “a senior Russian official.” The official said that he was merely relaying talk circulating in the Russian Ministry of Foreign Affairs, but what he’d heard was astonishing: people were saying that the Kremlin had intervened to block Trump’s initial choice for Secretary of State, Mitt Romney. (During Romney’s run for the White House in 2012, he was notably hawkish on Russia, calling it the single greatest threat to the U.S.) The memo said that the Kremlin, through unspecified channels, had asked Trump to appoint someone who would be prepared to lift Ukraine-related sanctions, and who would coöperate on security issues of interest to Russia, such as the conflict in Syria. If what the source heard was true, then a foreign power was exercising pivotal influence over U.S. foreign policy—and an incoming President.
As fantastical as the memo sounds, subsequent events could be said to support it. In a humiliating public spectacle, Trump dangled the post before Romney until early December, then rejected him. There are plenty of domestic political reasons that Trump may have turned against Romney. Trump loyalists, for instance, noted Romney’s public opposition to Trump during the campaign. Roger Stone, the longtime Trump aide, has suggested that Trump was vengefully tormenting Romney, and had never seriously considered him. (Romney declined to comment. The White House said that he was never a first choice for the role and declined to comment about any communications that the Trump team may have had with Russia on the subject.) In any case, on December 13, 2016, Trump gave Rex Tillerson, the C.E.O. of ExxonMobil, the job. The choice was a surprise to most, and a happy one in Moscow, because Tillerson’s business ties with the Kremlin were long-standing and warm. (In 2011, he brokered a historic partnership between ExxonMobil and Rosneft.) After the election, Congress imposed additional sanctions on Russia, in retaliation for its interference, but Trump and Tillerson have resisted enacting them.