The Department of Justice investigation into links between the Trump campaign and Russia isn’t just a scandal about the president’s conduct. The investigation could quickly engulf those surrounding the president — including his next in line.

The investigation is also about Michael Flynn’s conduct; that of campaign aides Roger Stone, Paul Manafort, and Carter Page; that of current White House aides like Jared Kushner and Jeff Sessions; and that of the vice president, who was, importantly, also the leader of the presidential transition.

Public discussion of the Comey scandal has rightly focused on whether or not President Trump has broken the law. If he has, indeed, committed obstruction of justice or another offense, that’s a remarkably serious development that puts impeachment on the table, as well as criminal prosecution once he’s out of office.

But Trump’s fate isn’t really a matter of legality. With most experts saying that federal prosecutors can’t charge him, the House and Senate are the only entities that can hold the president himself to account. Unless 218 representatives and 67 senators agree that it’s time for him to leave, he’ll stay in office and avoid criminal prosecution.

However, that does not mean special counsel Robert Mueller’s hands are tied. On the contrary, Mueller has broad authority to bring charges against basically anyone besides the president, up to and including Mike Pence if he’s found to have committed a crime.

Maybe all those people are innocent and committed no crimes. But it’s really not that uncommon for senior aides to the president to face felony charges. It’s not unheard of for vice presidents to face them either. With Mueller now in place, it’s time to start thinking about not just how this scandal will affect Trump’s presidency but how it will affect people close to him.

Michael Flynn, Carter Page, Paul Manafort, and Roger Stone could all be in serious trouble

The likeliest candidates for indictment, of Trump’s inner circle, appear to be former National Security Adviser Flynn and the trio of Stone, Manafort, and Page.

Flynn's case is perhaps the simplest. He was being investigated by the FBI for secretly lobbying for the Turkish government even before Trump was inaugurated; he told the transition he was being investigated on January 4, according to new reporting from the New York Times. According to my colleague Zack Beauchamp, there are up to three potential crimes with which Flynn could be charged:

Lying on his security clearance paperwork by failing to disclose $45,000 he got from the Russian government. According to House Oversight Committee Chair Jason Chaffetz and ranking member Elijah Cummings, Flynn really did this, and it’s a crime.

Filing an incomplete foreign agent registration form, by failing to fully disclose lobbying he did for Turkey or Russia; this is so far unproven.

Becoming national security adviser while still serving as an agent for Russia or Turkey.

The last is the most inflammatory charge, and until recently there was little evidence for it. But now it appears that Flynn shut down an Obama administration plan to retake ISIS's headquarters in Raqqa, a plan Turkey opposed because it required cooperation with Kurdish fighters. That occurred during the transition; the Obama administration asked the Trump team for their permission, and Flynn vetoed it. But it’s at least suggestive evidence that Turkey’s influence over Flynn may not have ended in November, which is what he’s currently claiming. If a prosecutor can show Flynn taking similarly pro-Turkish actions once in office, because he wanted to help Turkey, he could be in a lot of trouble.

Manafort, Page, and Stone, meanwhile, are at the center of the FBI's investigation into whether anyone on the Trump campaign coordinated with the Russian government to hack Democratic-connected email accounts and leak the contents so as to damage Hillary Clinton.

To be extremely clear, we don’t know if any of them committed any crimes. They are innocent until proven guilty. But we know that they’re being investigated.

Manafort, famously, worked for a government-aligned Russian billionaire on developing a "confidential strategy plan" designed to "greatly benefit the Putin government," by increasing support for Putin in the West, including among journalists. He had to resign as Trump's campaign chair after it came out that as recently as 2014 he had been lobbying for Ukraine's pro-Russian political party. Subsequent reporting has indicated that he was constantly in touch with senior officials in the Russian government throughout the campaign.

We also know that last summer, the FBI and the Justice Department got a FISA warrant to monitor Carter Page, who was then a Trump campaign foreign policy adviser; the agency thought that Page could be secretly working for the Russian government. Page has admitted to talking to agents for the SVR, Russia's equivalent of the CIA; has worked as an investment adviser for the Russian state-owned oil company Gazprom in the past; and met with the deputy prime minister of Russia in Moscow last summer.

Stone, meanwhile, a longtime Trump confidant who advised the campaign in its early stages, was in direct contact with Guccifer 2.0, which is the pseudonym the Russia hackers who targeted the Democratic National Committee and Clinton campaign chair John Podesta used; it's unclear if he knew he was talking to Russian intelligence, or if he was coordinating the release of emails. Stone also has said he was in touch with WikiLeaks, which released the emails, and sent a cryptic tweet on October 2, 2016, a few days before the Podesta emails were released:

Needless to say, assisting in hacking someone’s emails is illegal. It’s not clear that this is what Manafort, Page, or Stone did, but the warrant against Page strongly suggests that the FBI believes it’s worth investigating whether he did something illegal.

More senior aides could be in trouble too

If those four people alone faced charges, then Trump could perhaps weather the storm. None of them are in government anymore, and Trump can claim he has distanced himself from them. The case of Flynn is hardest — he was the only one to serve in the actual administration, and after Trump learned that he was being investigated, to boot — but Trump could maybe swing it.

But there are other people, currently in the administration, who could conceivably come into the crosshairs as the special counsel’s investigation proceeds.

Take Attorney General Jeff Sessions, who said under oath in his Senate confirmation hearings that he had no communications with Russian officials during the 2016 campaign. This is false; he spoke twice with the Russian ambassador to the US, Sergey Kislyak, as Sessions himself has conceded.

It’s not clear that this is enough to constitute perjury; as Benjamin Wittes, a national security law expert at the Brookings Institution, notes, perhaps Sessions meant he didn’t meet with Kislyak in his role as a Trump campaign surrogate, even though they met in Sessions’s capacity as a senator. But it could be perjury, and it raises the possibility that Sessions hasn’t been totally forthcoming with federal investigators, which would be an additional crime.

Or take senior adviser/presidential son-in-law Jared Kushner. Multiple reports have suggested that he encouraged Trump to fire FBI Director James Comey, a firing that may count as obstruction of justice on Trump’s part. Vice President Mike Pence and White House counsel Don McGahn reportedly also supported the firing. If Trump really did commit obstruction of justice by firing Comey, you could imagine his aides who supported that decision being investigated for conspiracy to obstruct justice, a crime for which Nixon White House aides H.R. Haldeman and John Ehrlichman were convicted during the Watergate trials.

Pence also, as head of the transition, knew that Flynn was under investigation and allowed him to be hired anyway. That itself isn’t a crime — but it’s damning and suggests that Pence is not just an innocent actor in all this.

While whether the president can be prosecuted is a matter of controversy, it is clear that vice presidents can be prosecuted while in office. That was the conclusion that the Justice Department came to in 1973 and again in 2000, in the Nixon and Clinton administrations. In the former case, Solicitor General Robert Bork concluded that Vice President Spiro Agnew could be prosecuted by US Attorney for the District of Maryland George Beall for accepting bribes as governor of Maryland. Beall eventually persuaded Agnew to take a plea deal; one of whose conditions was that Agnew had to resign the vice presidency.

Much earlier, in 1804, Vice President Aaron Burr was indicted for murder in both New York and New Jersey for killing Alexander Hamilton. There was never any controversy that this indictment was allowed.

All of which is to say, if Robert Mueller concludes that Mike Pence did something illegal, there is nothing stopping him from indicting and prosecuting Pence for it.

It’s not that uncommon for senior officials to face charges

The relatively clean governance of the Obama years conceals this to a degree, but it’s actually rather common for senior officials in presidential administrations to face prosecutions. Sometimes this is for crimes unrelated to their conduct in office (see Bush Domestic Policy Council Director Claude Allen's arrest for shoplifting), but often it isn’t:

Vice President Cheney’s chief of staff, Scooter Libby, was convicted of perjury, obstruction of justice, and false statements, and sentenced to 30 months in prison (a sentence that President Bush then commuted), as part of the scandal over the leaking of covert CIA officer Valerie Plame’s identity to the press.

Bush's Food and Drug Administration director, Lester Crawford, had to resign and pleaded guilty to conflict of interest charges surrounding stocks he owned.

Webb Hubbell, Clinton's associate attorney general, accepted a plea deal and pleaded guilty to not disclosing a conflict of interest after being repeatedly indicted by independent counsel Kenneth Starr.

Mike Espy, Clinton's agriculture secretary, was indicted for receiving improper gifts and acquitted at trial. His chief of staff, Ronald Blackley, was convicted of making a false statement and went to prison.

George H.W. Bush's Treasurer of the United States, Catalina Vasquez Villalpando, was found guilty of obstruction of justice and tax evasion and went to prison, as part of a scandal regarding gifts she received from a private company with business before the government

Many aides to Ronald Reagan — including National Security Advisers Robert McFarlane and John Poindexter, Secretary of Defense Caspar Weinberger, and Assistant Secretary of State Elliott Abrams — were indicted as part of the Iran-Contra scandal. McFarlane and Abrams were convicted and then pardoned by George H.W. Bush, Weinberger was pardoned before his trial, and Poindexter got his conviction overturned on appeal.

Reagan's former White House Deputy Chief of Staff Michael Deaver was convicted of perjury in 1987 because of statements he made about lobbying after he left the administration.

And there are more where that came from. This is just to say it would not be a big, shocking development for some of Trump’s aides to come under indictment. This is a pretty routine feature of American presidencies. If the special counsel investigation continues, we shouldn’t be surprised to see it become part of Trump’s.