Democrats have won control of the House of Representatives, according to calls by multiple media outlets — which means their days of standing by just helplessly watching President Donald Trump are gone.

The party’s House majority will allow them to launch subpoena-powered investigations into the president’s finances, Russian interference, administration ethics scandals, and so much more — and to halt the conservative legislative agenda in its tracks. They could even demand Trump’s long-concealed tax returns.

This very well may lead to all-out warfare between the House and the president. It’s possible that a crisis will unfold anytime they have to work together on a bill, that congressional investigators will unearth scandal after scandal, and even that an impeachment effort might be in the future.

But the Democratic takeover also provides Trump with some opportunities, should he decide he wants to take advantage of them. With his 2020 reelection campaign about to begin, he may well want to try to prove to voters that he can achieve something — by working with Democrats. This is what the likes of Bill Clinton — and, to some degree, even Richard Nixon — did to build a more popular image with the American people in the face of a hostile Congress.

Yet Trump is Trump, and he loves confrontation. Meanwhile, Democrats distrust the president and dearly hope to usher him out of office as soon as possible. On some matters like funding the government and raising the debt ceiling, though, they will have to figure out a way to work together — though getting there may not be easy.

Investigation time

The most imminent consequence of a Democratic House takeover is that there will be investigations galore. Democrats now have the power to make Trump’s life hell.

In August, Republicans were already supremely worried about this prospect. “Winter is coming,” one Trump ally told the Washington Post. Should the Democrats win the House, the source continued, “The White House will be under siege.”

That same month, Axios’s Jonathan Swan reported that congressional Republicans had compiled a lengthy, unsettling list of possible topics that a new Democratic majority could investigate. “These demands would turn the Trump White House into a 24/7 legal defense operation,” Swan wrote.

Indeed, the majorities in congressional committees have the ability to approve subpoenas: to demand documents or in-person testimony. And through the first two years of Trump’s administration, Democrats have been immensely frustrated that Republican majorities have been distinctly uninterested in investigating a great deal of seeming malfeasance.

For instance, the GOP had no interest in getting ahold of Trump’s tax returns or digging into how his business might be inappropriately intermingled with the presidency. They didn’t care much about a host of ethics and corruption scandals involving administration officials like Interior Secretary Ryan Zinke and Commerce Secretary Wilbur Ross. The House Intelligence Committee’s investigation of Russian interference into the election seemed designed mainly to protect Trump.

Democrats will surely use their subpoena power to change all this, aiming it at executive branch agencies, top Trump agency officials, and the Trump business. Just for a start:

House Intelligence Committee Chair Rep. Adam Schiff (D-CA) made it clear when he was in the minority that he wanted to open a more aggressive Russia investigation.

House Ways and Means Chair Rep. Richard Neal (D-MA) could well try to get Trump’s tax returns.

House Foreign Affairs Committee Chair Rep. Eliot Engel (D-NY) could investigate Trump’s Saudi Arabia policy in the wake of Jamal Khashoggi’s murder.

House Judiciary Committee Chair Rep. Jerrold Nadler (D-NY) will be on the lookout for inappropriate interference with the Justice Department.

These investigations can really matter — as we saw after Republicans won the House under President Obama. The new GOP majority’s much-mocked, seemingly endless series of investigations into the administration’s handling of the Benghazi attacks eventually surfaced some information that proved very useful to them: that Hillary Clinton had used a private email server for her work as secretary of state. The ensuing scandal dogged her campaign and may have doomed it. Democrats could well find a similar political cudgel.

Even if they don’t, the investigation process itself will be grueling for the Trump administration as they spend countless hours attempting to respond to congressional demands and top staffers are hit with legal bills. Trump may well fight back too, by trying to assert executive power to defy these investigations.

The legislative battles will be about potential bipartisan compromises and must-pass bills

When it comes to legislation, the Democratic House majority means that Republicans can no longer pass even a single bill unless Democrats agree to let them. And they won’t just need to pick off the most moderate House Democrats — the party leaders will control what gets to the floor in the first place. So consider the conservative legislative agenda dead — no more Obamacare repeal, no more huge tax cuts, no big cuts to Medicaid or food stamps.

The legislative drama will instead focus on what, if anything, Trump and Democrats can manage to do together.

You might think the answer would be nothing. And indeed, Trump’s political strategy so far has been monomaniacally focused on conservative base voters. If he continues in this vein, he’ll have little desire to work with Democrats.

But there is another possible path forward for Trump. He might be tempted by the example of Bill Clinton, who tacked to the right after losing Congress in 1994, signed welfare reform into law, and then won reelection in 1996. And Trump is so indifferent to policy details that he could make Democrats an offer they’d have a tough time turning down.

Conservative White House staffers like John Kelly and Stephen Miller could be a major obstacle to bipartisan dealmaking. But if Trump decides this is something he wants, he can simply replace them with new top staffers. Turnover among top White House staffers is historically common after a midterm defeat — if Trump decides he wants someone who can try to cut a deal with Democrats, he could make staffing changes to help him do that.

For instance, after Republicans took the House in 2010, Obama brought in Bill Daley as his new chief of staff. Daley was a less partisan and controversial figure than Obama’s first chief, Rahm Emanuel, and the expectation was that he’d be well-suited to bipartisan dealmaking. As it turned out, Daley lasted less than a year in the job, and his performance was panned — but it was, at least, an attempt at a new approach.

There are a few issues where Trump, Republicans, and Democrats can envision a potential compromise. Most obvious among these would be an infrastructure spending bill of some kind — this is something Trump said he wanted during the campaign but that congressional Republicans had little enthusiasm for. Immigration and specifically the Deferred Action for Childhood Arrivals program are another possibility. A few have even floated gun control, which Trump occasionally goes off message on — though that seems less likely, given the GOP’s staunch alliance with the National Rifle Association.

Yet though moderate Democrats might be eager to make deals in areas where there’s common ground, Democratic leaders may be wary of helping Trump achieve a big legislative victory that could improve his reelection chances. It would take a very savvy dealmaker to overcome all Democrats’ incentives not to hand Trump a win, and Trump has not proven himself particularly adept at bipartisan dealmaking so far.

In any case, there will be several more or less guaranteed legislative showdowns on “must-pass” bills like funding the government and raising the debt ceiling. Trump needs new bills to pass here or he’ll face either a government shutdown or a potential financial crisis.

Back when Republicans took the House under President Obama, they knew they couldn’t pass conservative bills on their own, so instead they tried to use these measures where they believed they had “leverage” over the White House to advance their agenda. The strategy had mixed success — Obama did sign on to major spending cuts to raise the debt ceiling in 2011, but he successfully fended off Republicans’ efforts to demand government funding bills that would have defunded Obamacare in 2013.

It’s likely House Democrats will make a similar play. We already got a sneak preview of this in early 2018 when Senate Democrats tried to insist they’d filibuster any government funding bills unless DACA was protected. They caused a brief government shutdown over it, but then essentially chickened out.

Now a liberal Democratic House majority might feel more empowered to play hardball. But Trump generally prefers to be the aggressor — so expect him to stretch his executive powers here as well. Some liberal commentators, for instance, urged Obama to use a legal loophole to mint a platinum coin rather than make concessions to Republicans in exchange for raising the debt ceiling. Obama didn’t want to do that — but Trump might.

The specter of impeachment

Democrats have generally tried to downplay the possibility that they might try to impeach President Trump throughout the campaign. And indeed, so far, there seems to be little support among Democrats in Congress for going that far.

Last year, only 58 Democrats voted to support even debating Trump’s impeachment. It is unclear how many would actually vote for it at this point, and most have voiced caution. “Everybody wants to jump to the end of the analysis, which is impeachment, but I think we’ve got to take it step by step here,” Rep. Jamie Raskin (D-MD) told Politico this summer.

But this measured approach could change very quickly if new and damning information were to emerge — whether from special counsel Robert Mueller’s Russia probe, from the investigation tied to Michael Cohen, or from any of the newly empowered Democratic investigators in Congress. Former close Trump associates Paul Manafort, Michael Cohen, Rick Gates, and Michael Flynn have all been cooperating with Justice Department investigators for some time, with the full extent of each person’s cooperation unclear.

It only takes a simple majority of the House to impeach a president. And they can really impeach him for whatever they want — the Constitution refers to “high crimes and misdemeanors,” but it’s up to Congress to determine what those are.

But it’s important to keep in mind that “impeachment” is not the same thing as “removal from office.” Actually convicting and removing Trump would be the Senate’s job — and it would take a two-thirds majority, 67 senators. (It has never yet happened — both impeached presidents, Andrew Johnson and Bill Clinton, were acquitted in the Senate.)

That’s one of the reasons Democrats have been so wary about raising their voters’ expectations on impeachment: because if Senate Republicans continue to support Trump, the quest will inevitably end in failure.

Still, if truly incriminating things come out of the investigations, House Democrats will surely feel pressure from their base voters to take action — meaning 2019 could be a very interesting year for politics indeed.