2016 might not provide the same levels of legislative and leadership drama on Capitol Hill — no Speaker John Boehner (R-Ohio) to kick around anymore, spending caps to argue over (for now), or shutdowns in the offing (at least until September). But lobbyists are gearing up for some tough fights, nonetheless, the contours of which are already taking shape.

Here’s our look at what are likely to be the biggest legislative fights of 2016:

Speaker of the House Paul Ryan pushed for approval of fast-track trade promotion authority, and could — if he decides to support it — be a big help to the White House on TPP. (Photo by Win McNamee/Getty Images)

1. Trans-Pacific Partnership:

TPP, the sweeping trade deal reached in October between the United States and 11 other Pacific Rim nations, is expected to be hotly contested, both from members of Congress and from a wide swath of interest groups. It will be the biggest showdown among lawmakers, interest groups and the White House in 2o16.

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One of the biggest problems for deal advocates is timing: the Obama administration initially planned to send the deal to Capitol Hill for a vote in the spring or summer of 2016. But there’s one big vote of no confidence on this election-year plan: Senate Majority Leader Mitch McConnell (R-Ky.) said in December that the deal is unlikely to come before Congress prior to the election. But new Speaker Paul Ryan (R-Wis.) was a big ally to the White House in pushing fast-track trade promotion authority and could help Obama if he supports TPP (which is now unclear). The agreement is complicated by the fact that several leading presidential contenders oppose it, including Hillary Clinton, Donald Trump, and Sen. Ted Cruz (R-Texas).

Meanwhile, TPP’s foes are multiplying. Environmental activists are gearing up to fiercely fight the pact, saying it would weaken governments’ abilities to combat climate change by encouraging the production and export of fossil fuels, natural gas and crude oil. U.S. automakers criticize the pact for not going far enough to address currency manipulation. Labor unions are concerned the deal would encourage the outsourcing of U.S. jobs.

However, TPP will likely get significant support from the business community, which would largely benefit from expanding markets abroad.

Read  more:

[Industry, labor and environmental groups gear up to oppose TPP trade deal]

[McConnell warns that trade deal can’t pass Congress before 2016 elections]

[At Paris climate summit, environmentalists lobby against Trans-Pacific trade deal]

House Minority Leader Nancy Pelosi is pressing Republican leaders to give Puerto Rico some relief before March 31 of next year. (AP Photo/J. Scott Applewhite)

2. Puerto Rico:

The U.S. territory is struggling to repay billions of dollars in debt, and the island’s top officials are aggressively lobbying Congress to  to allow Puerto Rico to restructure its debts in bankruptcy — a tactic that is riling many bondholders. The Puerto Rican government’s lobbying strategy hasn’t yet paid off, but legislative efforts to address the fiscal crisis did gain some bipartisan traction right before the holiday recess, when Senate GOP chairmen for the first time introduced a bill offering some aid to the island.

But the issue was excluded from the year-end spending package, to Democrats’ dismay. Yet there’s a glimmer of hope heading into the new year: both Speaker Paul D. Ryan (R-Wis.) and McConnell pledged to address the issue early next year. It’s a small victory for House Democrats, who pressed for quick consideration of the aid as a condition to back the omnibus package.

Read more:

[GOP bill aiding Puerto Rico debt crisis could prompt bipartisan solution]

[Competing lobbying campaigns clash over Puerto Rico debt crisis]

Charles Koch, 79, is photographed in his office at Koch Industries in Wichita, Kansas, on Wednesday, July 29, 2015. Koch Industries is working with Democrats and Republicans to reform the criminal justice system. (Photo by Nikki Kahn/The Washington Post)

3. Criminal justice reform:

Momentum to reform sentencing and other aspects of the criminal justice system has been building throughout 2015, getting attention from the White House, members of both parties in Congress and presidential candidates. The effort unites unusual allies from the White House to Koch Industries.

The House and Senate are working on measures to reduce minimum sentences for drug offenders — and 2016 could yield significant progress. One sticking point called “mens rea,” supported by the Kochs, is controversial because it would require prosecutors to prove that white-collar defendants “knew, or had reason to believe, the conduct was unlawful.” But the White House and Koch interests have agreed “mens rea” should be jettisoned if it jeopardizes the entire package.

Many interest groups care deeply about reform, including social justice advocates and the business community, the latter of which has a stake in how potential reforms may affect white-collar prosecutions.

Read more:

[Obama convenes meeting on criminal justice reform to buoy bipartisanship]

A sign for Aetna Inc., sits atop a building at the company headquarters in in Hartford, Conn. The health insurer wants to buy competitor Humana Inc. in a $37 billion deal the companies say would create the second-largest managed care company, it was announced Friday, July 3, 2014. (AP Photo/Jessica Hill, File)

4. Mega-mergers:

Merger and acquisition activity reached a record high in 2015, with a number of industry leaders announcing proposed combinations, including health insurers Aetna and Humana, and Anthem and Cigna; beer giants Anheuser Busch InBev and SABMiller; and Time Warner Cable and Charter Communications.

In some cases, the mergers would mark uncharted territory in their respective sectors in terms of market share and value. 

Proposed mergers are reviewed, and can be blocked, by the Justice Department’s Antitrust Division, in conjunction with the Federal Trade Commission. The Senate Judiciary Subcommittee on Antitrust, Competition Policy and Consumer Rights, and the House Judiciary Subcommittee on Regulatory Reform, Commercial and Antitrust Law typically hold hearings to question executives of the merging companies and to hear concerns from those opposing the deals. Expect to see plenty of such panel grillings in 2016.

Many of the companies have already lined up lobbyists to urge antitrust regulators to green-light the deals. Some of the mergers have already been contested — the American Medical Association and American Hospital Association are urging the Justice Department to reject both the Aetna-Humana and Anthem-Cigna deals, arguing they would quash competition and hurt consumers.

Sen. Jim Inhofe, R-Okla.. is chairman of the Senate Environment and Public Works Committee and an avowed climate change skeptic. (AP Photo/Andrew Harnik)

5. Environmental regulations:

The year-end spending bill includes funding to implement many environmental measures advanced by the Obama administration, including the “Waters of the U.S.” rule (meant to protect waterways from pollution), the Clean Power Plan (meant to reduce carbon emissions from power plants) and new ozone standards.

But the fight will undoubtedly continue between the Obama administration and Congress over these measures, with Obama dedicated to implementing them through executive action and the Republican-controlled House and Senate bent on stopping him.

The fate of the Clean Power Plan may ultimately be decided in the courts. Twenty-seven states and a number of industry groups — including the U.S. Chamber of Commerce, utilities and coal companies — have sued the Obama administration over the new regulations. Environmental groups are siding with the Environmental Protection Agency in defending the rules.  The lawsuits are expected to stretch well beyond 2016.

The international climate pact reached in Paris earlier this month does not need approval from Congress, but Republicans could continue opposing funding that is critical to implementing the pact. They had hoped they could block U.S. contributions to the Green Climate Fund — a U.N.-founded global pool of money meant to help poorer countries combat climate change — in the year-end spending bill, but that effort failed. Still, some GOP lawmakers say they could challenge the funding in the 2017 appropriations process.