President Trump spent 2017 trying to bat back accusations that his campaign colluded with Russia. But 2018 could be even worse, with potential indictments of Trump's closest aides — and possibly the president himself.

Mueller could learn new information about possible collusion from Trump’s former campaign Chair Paul Manafort or former national security adviser Michael Flynn, two men Mueller charged with crimes (Manafort pleaded not guilty, but Flynn pleaded guilty). The special counsel could indict even more people in Trump’s orbit, including his son-in-law and special adviser Jared Kushner.

Or even worse for Trump, Mueller could charge him with obstruction of justice based on his firing of former FBI director James Comey in May 2017 after Comey declined to stop an investigation into Flynn.

Trump, for his part, could escalate things by firing Mueller or deputy attorney general Rod Rosenstein for not removing the special counsel on Trump’s behalf. Either move could trigger a historic political crisis — and fuel calls for Trump’s impeachment.

So what follows are the key things to watch for in the Trump-Russia investigation in 2018. Depending on how they play out, the president — and the country — may face an even bigger legal and political crisis than in 2017.

Will Trump fire Mueller?

The top question of 2017 will likely remain the top question of 2018. That’s because Mueller’s probe is drawing closer to Trump’s top aides — and to Trump himself.

Last October, two of Trump’s former campaign aides were indicted, and a third pleaded guilty on false statement charges. Then, on December 1, Flynn pleaded guilty to a false statements charge, and made a deal to cooperate with Mueller’s team in the process (more on that in a bit).

The president has repeatedly complained about the investigation both in public and in private, and some of his conservative allies in and out of government are already making the case to fire the special counsel. So there is a chance that Mueller is dismissed this year.

But “firing Mueller” isn’t so simple. To get rid of Mueller, Trump would also have to get rid of Rosenstein. Rosenstein, who is effectively Mueller’s boss, has repeatedly made it clear that he sees no good cause to fire Mueller. So to get to Mueller, Trump could ask Rosenstein to fire Mueller, which may cause Rosenstein to resign instead of doing the deed. Or Trump could simply fire Rosenstein.

So if Trump does want to remove the special counsel, he may need to go through several Justice Department officials until he finds one willing to carry out his order.

That would get very messy very quickly. A fight on Capitol Hill would almost surely break out between liberals claiming Trump obstructed justice and conservatives suggesting Trump was right to dismiss Mueller.

For now, Trump insists he has no intention of firing Mueller, but that could change next year as the special counsel moves further into Trump’s inner circle.

Which leads to another question ...

Will Jared Kushner get indicted?

On December 1, Mueller released a court document that described a “very senior” transition official asking Flynn to persuade the Russian ambassador to the US to help stop a UN Security Council vote on Israeli settlement policy.

Multiple reports confirmed that the official was Kushner. That makes perfect sense: Kushner was an extremely important figure during the transition, and reporting at the time suggested that he was involved in Trump team deliberations on the settlements issue.

That was just one of many times Kushner’s name has come up in connection with the Russia matter. There was the meeting he had with ambassador Kislyak during the transition in which they reportedly discussed setting up a secret backchannel of communication. There was the Donald Trump Jr.-brokered meeting with a Russian lawyer who’d promised “dirt” on Hillary Clinton during the campaign. And there are the reports that Kushner urged Trump to fire then-FBI director James Comey.

Kushner also amended his financial disclosure forms at least 39 times. Those forms are important: They are needed for Kushner to get a security clearance. Vox’s Zeeshan Aleem reported that Kushner originally failed to report the Trump campaign’s communications with Russia; his meetings with Russians; his business ties with Russians; and more. On top of that, Kushner used a private email account to conduct government business.

One of the people Mueller hopes will provide more information on Kushner is Flynn, and Flynn may just be willing to cooperate ...

What, exactly, is Flynn giving Mueller?

Flynn’s plea deal was the most significant moment in Mueller’s probe last year.

Flynn was the first person who had actually served in the Trump White House to admit he broke the law. And he wasn’t just any old official: His role as national security adviser made him one of the most powerful people in the administration. The retired three-star general temporarily had enormous sway over Trump’s early policy and personnel choices.

Due to his unique ties to both the Trump campaign and the Trump White House, Flynn is particularly well-suited to answer the two central questions in the Mueller probe: Did the Trump campaign knowingly collude with Russia, and did Trump obstruct justice by trying to limit or derail the FBI’s investigation?

So far there is no public evidence that Flynn has provided Mueller any valuable information. But some legal experts believe Mueller is using Flynn to get closer to the president.

“We know from public reports that Flynn has a ton of criminal exposure, and yet he’s pleading guilty to a relatively minor crime. I’m confident Flynn is singing like a bird to Mueller,” Andy Wright, a law professor at Savannah Law School, told Vox’s Sean Illing.

That could be very bad news for Kushner, for instance, and maybe even the president further down the line. Their fortunes might worsen if someone else turns on them ...

Does Paul Manafort flip?

Mueller indicted former Trump campaign manager Paul Manafort and his business associate Rick Gates — two top Trump staffers during the 2016 campaign — in federal court last year.

The two men now face a total of 12 charges that mostly focus on alleged money laundering, failure to disclose their financial assets, and false statements regarding their work for the government of Ukraine and a Ukrainian political party.

The indictment alleges that Manafort laundered more than $18 million since 2006. However, the charges don’t actually have anything to do with the question of Russian interference during the election. Manafort and Gates pleaded “not guilty” to the charges.

Still, going after Manafort has its own logic for Mueller’s probe. First, the charges could get Manafort to admit he played a role in, or knew about, any potential collusion between Trump’s team and the Russian government during the campaign.

And second, if Manafort does have any useful information, perhaps Mueller’s team could convince or compel him to share that information — maybe because of these other charges.

Manafort may instead choose not to give up any incriminating information about Trump or people close to him — if he has any — perhaps in hopes of a presidential pardon. But Politico reported in August 2017 that Mueller’s team started working with New York Attorney General Eric Schneiderman, who had been conducting his own investigation of Manafort’s finances.

That’s important: President Trump could theoretically pardon Manafort for any federal offense — but not state offenses. So as long as the prospect of state charges are hanging over Manafort’s head, he could well have a powerful incentive to cooperate.

Does Trump get charged with obstruction of justice?

This is one of the biggest questions hanging above the entire Mueller probe, and it may yet take years to find out one way or the other.

But bits and pieces keep coming out that brings this question back to the forefront. On December 2, for example, Trump tweeted the following:

I had to fire General Flynn because he lied to the Vice President and the FBI. He has pled guilty to those lies. It is a shame because his actions during the transition were lawful. There was nothing to hide! — Donald J. Trump (@realDonaldTrump) December 2, 2017

Recall that Trump fired Flynn on February 13, 2017. It was that very morning when Trump cleared a room of advisers and asked to speak with Comey alone. “I hope you can see your way clear to letting this go, to letting Flynn go,” Trump said, according to Comey’s later testimony and a memo he wrote at the time.

Comey said that he “understood the President to be requesting that we drop any investigation of Flynn in connection with false statements about his conversations with the Russian ambassador in December.” Trump denies ever saying this.

Trump’s own tweet suggests that he was well aware Flynn was facing serious legal jeopardy — and went straight to the head of the FBI to ask him to back off.

Trump’s outreach to Comey already looked bad. But Trump’s interference looks even worse if, as the tweet says, he knew not only that Flynn was under investigation but that he outright “lied to” the FBI. At that point he wouldn’t just be trying to protect an ex-aide who he thinks did nothing wrong — he’d be trying to argue that a guilty man shouldn’t face justice.

The White House, however, claims that one of Trump’s lawyers — John Dowd — actually tweeted the message, not Trump.

Still, the tweet is an indicator that Trump may have obstructed justice when he fired Comey. Ironically, that move led to Mueller’s appointment as the special counsel. Any legal trouble that may come Trump’s way in 2018 will largely stem from the president’s blunders.