(CNN) President Donald Trump called for special counsel Robert Mueller's firing last June, according to one person familiar with the matter.

But the President never went through with the order because White House counsel Donald McGahn threatened to quit instead of carrying out the order, the source said.

Trump's firing of FBI Director James Comey in May 2017 -- amid the bureau's investigation into ties between Trump campaign associates and Russia -- redirected the focus of ethical and legal scrutiny squarely on the White House.

Amid accusations of "Nixonian" behavior and as members of Congress in both parties raise questions about Trump's actions, one major player is likely to find himself at the center of the White House's efforts to stave off those accusations and remain on firm legal ground: McGahn, the White House counsel.

But McGahn, who previously served as the Trump campaign's top attorney, had already found himself the subject of scrutiny, after former acting Attorney General Sally Yates' congressional testimony raised fresh questions about McGahn's role in the saga involving former national security adviser Michael Flynn.

Flynn quit after news reports revealed that Yates had warned McGahn in late January 2017 that Flynn had misled White House officials about details of his conversations with the Kremlin's US ambassador Sergey Kislyak.

Yates explained that she met with McGahn in person on January 26, 2017, to tell him that she had information that statements by Vice President Mike Pence, based on his conversations with Flynn, were false, and Flynn was susceptible of being "essentially blackmailed by the Russians."

Former White House press secretary Sean Spicer told reporters in February that Yates merely wanted to give McGahn a "heads up" and that McGahn "informed the President immediately."

McGahn conducted "exhaustive and extensive questioning of Flynn," according to Spicer, and McGahn concluded that Flynn had not violated the law.

Yates' testimony immediately renewed questions about McGahn's handling of the situation: What exactly did he do with the information; did he ever sift through the evidence the Justice Department offered to show him to support the conclusion that Flynn had been compromised; who else was told of Yates' warning and when, and finally, what deliberation took place that ultimately allowed Flynn to keep his job for 18 days after Yates' revelation?

CNN reported in December that McGahn told Trump in January 2017 he believed Flynn had misled the FBI, lied to Pence and should be fired, according to a source familiar with the matter.

McGahn later tried to dissuade Attorney General Jeff Sessions from recusing himself from the investigation into any coordination between Russian meddling in the 2016 election and Trump campaign associates, according to a source close to Sessions.

Finally, late last year McGahn was interviewed in special counsel Mueller's probe.

A former campaign finance lawyer by trade, McGahn now continues finds himself in the midst of a multiple political firestorms, with a client that blasts out tweets on the very hot-button topics McGahn has been tapped to manage.

To say that McGahn has his work cut out of him is, therefore, an understatement.

Election litigator-turned-chief White House lawyer

Prior to working at 1600 Pennsylvania Avenue, McGahn was a partner specializing in campaign finance at Jones Day in Washington, general counsel for Trump's campaign, in-house counsel for the National Republican Congressional Committee for years and former commissioner for the Federal Election Commission from 2008-2013.

"He rewrote virtually all of the FEC's procedures for audits, enforcement matters and advisory opinions, which provide for an unprecedented amount of due process," according to a statement from Jones Day announcing his departure from the firm.

More than simply an aggressive litigator, he also has been known to have a flair for the dramatic at times. Once while at the FEC, he tore pages of regulations out of book at a public hearing to drive home his point during a rant against his Democratic colleagues.

And unlike many of his straitlaced former colleagues who display diplomas from their Ivy League law schools on their walls, McGahn went to Pennsylvania's Widener University, used to keep his hair relatively long and played in an '80s cover band, according to a Washington Post profile

"Don has a brilliant legal mind, excellent character and a deep understanding of constitutional law," Trump said in a statement announcing his appointment as White House counsel back in November 2016. "He will play a critical role in our administration, and I am grateful that he is willing to serve our country at such a high-level capacity."

CORRECTION: This story has been updated to reflect McGahn was a former commissioner for the FEC from 2008-2013.

This story was originally published in February 2017 and has been updated to reflect new reporting on McGahn.