Donald Trump is unique among modern Presidents in that he has no significant legislative accomplishments to show for ten months after taking office. Year one is when Presidents usually make their mark, especially if they came into office with unified control of the government, as Trump and his party did. Presidents in the first year of their first term are often at the peak of their popularity, have the biggest margins in Congress, and are free from the scandals and intense partisanship that start to gather around them later and make governing ever more difficult. By the second year, a President’s legislative agenda becomes complicated by the hesitancy of members of Congress to take risky votes as midterm elections approach, particularly if a President is unpopular. The math is stark: on average, modern Presidents have historically lost thirty House seats and four Senate seats in their first midterm elections.

Trump is governing well below the optimal levels of recent successful first-year Presidents. In 1981, Ronald Reagan’s first year in office, Reagan was so personally popular that he was able to convince a Democrat-controlled Congress to pass a major tax cut. In 1993, Bill Clinton used a Democratic Congress to pass a major economic plan, the Family and Medical Leave Act, gun legislation, and NAFTA, though his signature health-care bill eventually failed. (The political cost was high: in midterm elections the following year, Clinton lost his Democratic Congress for the rest of his Presidency and was later engulfed in scandals that slowed his agenda.) In 2001, George W. Bush, who also started with a Congress controlled by his own party, passed a major tax cut and a significant rewrite of federal education policy, two pieces of legislation that came with significant support from Democrats. Barack Obama came into office, in 2009, with large Democratic majorities, high approval ratings, and a massive economic crisis, all of which he leveraged to pass the most ambitious first-year agenda of any President since Lyndon Johnson, including an enormous economic-stimulus package and major reforms of the financial regulatory system and health care. (The final version of Obamacare, after some drama, was actually signed into law in March of his second year.)

Trump’s first year has been different. He has a record-low approval rating. He is mired in scandal. And he so far has no major legislative accomplishments. He looks like a President in his eighth year rather than one in his first. All of this makes December crucial for the White House.

From now until the new year, Congress will be jammed with legislative activity that may make or break Trump’s first year in office. Most of the attention has focussed on Trump’s tax-cut legislation, which is deeply unpopular according to public-opinion polls but which Republicans believe is essential to pass in order for them to have something to show for the year. But there are many other politically consequential bills that must be passed in the weeks ahead. On December 8th, the money to fund the federal government runs out. Staff members for the four top Democratic and Republican leaders have been meeting with the White House for weeks to negotiate a deal. On Tuesday, these leaders—Paul Ryan, Nancy Pelosi, Mitch McConnell, and Chuck Schumer—will meet with Trump at the White House about the issue.

Schumer and Pelosi have been maneuvering for this moment all year, and they have significant leverage. The Republican Party, despite unified control of Congress, does not have the votes to pass bills to fund the government in either the House, where many conservatives refuse to support annual appropriations bills, or the Senate, where they need sixty votes but have only fifty-two Republicans. For several years, a coalition of mostly Republican defense hawks, who want higher levels of Pentagon spending, and Democrats, who want higher levels of discretionary spending, have joined forces to provide the votes for the annual appropriations bills. Pelosi and Schumer will not deliver those Democratic votes without extracting a price from Trump and Republicans.

There are three major pieces of legislation that Democrats want: a bipartisan fix for Obamacare, a legislative fix for the Obama-era DACA program that Trump recently ended, and the extension of a popular health-care program for children—SCHIP—that recently expired.

Some liberal Democratic senators have said that they won’t vote to fund the government unless the DACA fix is included, though that is not yet a Party-wide position. As for the Obamacare fix, which is known as Alexander-Murray, after the two senators who negotiated it, the current version of the G.O.P. tax-cut bill includes a repeal of Obamacare’s individual mandate, which would hobble Obamacare rather than fix it. The politics for Trump are tricky. Senator Susan Collins, of Maine, a shaky vote on the tax bill, has hinted that she wants the bipartisan health-care legislation passed as the price for her vote on any tax bill that repeals the mandate. Schumer has said that passing a mandate repeal would blow up the Alexander-Murray Obamacare fix. In other words, Schumer is not going to help pass the health-care fix as a way to grease the skids for McConnell to secure Collins’s vote on tax cuts. Trump is likely going to have to give ground on one or more of these Democratic priorities.

“Any Republican senator who thinks they can pass the individual mandate [repeal] and then turn around and get Murray-Alexander passed is dead wrong,” Schumer said on November 15th, after McConnell added the Obamacare-mandate repeal to the Republican tax bill.

The last time Trump cut a deal with Schumer and Pelosi was in May, when the leftover spending bills from the previous year were negotiated and passed to keep the government operating through the end of the fiscal year. In fact, this was arguably the most significant piece of legislation of Trump’s first year, and it was widely considered to be an enormous success for the Democrats because it included high levels of discretionary spending opposed by Trump and no funding for the border wall that he requested. Trump was so angry about the coverage that he tweeted that perhaps there needed to be a government shutdown the next time the two sides entered spending negotiations. “The reason for the plan negotiated between the Republicans and Democrats is that we need 60 votes in the Senate which are not there!” Trump said in a series of tweets. “We either elect more Republican Senators in 2018 or change the rules now to 51%. Our country needs a good ‘shutdown’ .”

Tuesday’s meeting at the White House between Trump and congressional leaders from both parties is meant to avoid a December 8th government shutdown. How much Republicans are willing to give Democrats may depend on the status of the G.O.P. tax bill. There are at least half a dozen G.O.P. senators with serious policy concerns regarding the tax proposal. And there are three Republican senators—John McCain and Jeff Flake, of Arizona, and Bob Corker, of Tennessee—who dislike Trump so much that they may be looking for reasons to oppose any legislation that empowers his Presidency. Republicans already have a ready-made conservative reason: the proposed tax changes will increase the deficit by $1.5 trillion.

If the tax bill is cruising through the Senate—McConnell wants a vote next week—there may be less incentive for Republicans to risk a shutdown. But if it dies next week, or is delayed, Trump will be under intense pressure to avoid ending the year with no major legislative accomplishments—and the chaos of a government shutdown. In order to keep the government running, Trump would have to strike another deal with Pelosi and Schumer and sign a bipartisan spending deal that includes major Democratic priorities.

As a result, Trump would end his first year in office with no Republican legislative accomplishments and two deals with Pelosi and Schumer that boost the Democratic agenda. If that seems likely to happen, it would enrage conservatives and the Republican base. For Trump, December could be the month that makes or breaks his first year in office.