Lawmakers will return to Washington in January with a full plate of controversial issues that could gum up the early days of the President-elect Donald Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE's term.

GOP lawmakers and the Trump administration are eager to move quickly after winning control of both Congress and the White House for the first time in nearly a decade.

But divisive fights with Democrats, and within the party, could grind Congress to a halt, and quickly test that ambitious GOP agenda.

Here are five fights awaiting lawmakers and Trump next year:

Trump's Cabinet

Democrats are digging in for a fight over Trump’s slate of Cabinet nominees, arguing the picks reflect larger concerns they have about the incoming president.

Fifteen Senate Democrats, as well as Independent Sen. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (Vt.), issued a rare joint statement calling on the confirmation hearings to be put off until lawmakers could thoroughly vet the picks.

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Democrats say that would include passing an FBI background check, turning over financial disclosure forms and an ethics agreement, and generally satisfying “reasonable requests for information.”

Republicans, though, are aiming to move the picks quickly after they are nominated.

Democrats face an uphill battle to block any of Trump’s nominees. Republicans will control 52 seats in the Senate, meaning Democrats would need three GOP votes and no defections to defeat any nominations.

But they aren’t backing down from the fight, accusing Trump of compiling a “rigged" Cabinet. Democrats argue picks like Rep. Tom Price (R-Ga.) to lead the Department of Health and Human Services undercuts Trump’s pledge to not cut social welfare programs.

“If Republicans in the Cabinet or in Congress declare a war on seniors and working families, Democrats will not let them win that fight,” said Sen. Charles Schumer Chuck SchumerCruz blocks amended resolution honoring Ginsburg over language about her dying wish Senate Democrats introduce legislation to probe politicization of pandemic response Schumer interrupted during live briefing by heckler: 'Stop lying to the people' MORE (D-N.Y.), the incoming Senate Minority Leader.

Democrats are also expected to try to change the Senate rules to require Cabinet nominees to release tax returns from three years.

Russia policy

Lawmakers and Trump appear to be on a collision course over Russia.

Senators, wary of Trump’s warmer comments about Russian leader Vladimir Putin, were already planning to take a harder line than his administration, including potentially new sanctions.

But Trump’s decision to pick Rex Tillerson to lead the State Department paired with election hacking allegations are bringing the fight into the forefront.

Democrats, and some hawkish Republicans, worry the pick signals Trump will be soft on Moscow. Tillerson as Exxon CEO had business dealings with Russia and is believed to be friendly with Putin.

Sen. Lindsey Graham Lindsey Olin GrahamSenate GOP aims to confirm Trump court pick by Oct. 29: report The Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Senate GOP sees early Supreme Court vote as political booster shot MORE (R-S.C.) warned he will be a "bit of a hard ass" on Russia and is calling for “crippling” sanctions. Sen. Ben Cardin Benjamin (Ben) Louis CardinCongress must finish work on popular conservation bill before time runs out PPP application window closes after coronavirus talks deadlock Congress eyes tighter restrictions on next round of small business help MORE (D-Md.), the top Democrat on the Foreign Relations Committee, is also working on a bipartisan bill to crackdown on Russia.

The committee will also dig into the hacking allegations as part of a larger series of public and closed-door hearings beginning in January on the U.S.’s posture on Russia.

Trump has dismissed the CIA's findings that Russian hackers tried to help him win. Lawmakers widely agree that the matter should be probed but are divided on who should investigate.

The Intelligence Committee, with the support of Senate Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellFEC flags McConnell campaign over suspected accounting errors Poll: 59 percent think president elected in November should name next Supreme Court justice Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' MORE (R-Ky.), and the Armed Services Committee are also expected to probe the CIA’s findings.

But a bipartisan group of lawmakers — led by Schumer and Sen. John McCain John Sidney McCainThe Memo: Trump's strengths complicate election picture Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' Cindy McCain: Trump allegedly calling war dead 'losers' was 'pretty much' last straw before Biden endorsement MORE (R-Ariz.) — is likely to keep pushing for a select committee.

ObamaCare repeal

Republicans will lay the groundwork in January for repealing the Affordable Care Act, kicking off a new stage in the long fight over President Obama’s signature law.

McConnell told reporters that the ObamaCare repeal effort would be the first item on the Senate’s agenda.

The legislation wouldn’t repeal the Affordable Care Act. Instead, Republicans are expected to pass a shell budget that includes instructions for rolling back large swaths of ObamaCare under reconciliation.

The process allows lawmakers to repeal parts of the law under a simple majority and bypass the Senate’s 60 vote threshold. The House is also expected to vote on the reconciliation instructions on Jan. 9th, according to a timetable released by the Energy and Commerce Committee.

Though GOP lawmakers are eager to repeal the law there’s little consensus on the details of when or how to replace it.

Sen. John Cornyn John CornynThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting Liberal super PAC launches ads targeting vulnerable GOP senators over SCOTUS fight Senate GOP faces pivotal moment on pick for Supreme Court MORE (R-Texas) told reporters that the Senate was eyeing a three-year ObamaCare off-ramp, but that wasn’t locked down. That plan would likely run into trouble with the House Freedom Caucus, who have signaled they want a repeal during the 115th Congress.

Republicans will also likely need 60 votes in the Senate to pass a replacement plan, meaning they will need to win over a handful of Democrats.

While Schumer blasted the GOP effort to repeal ObamaCare, telling Republicans to “bring it on," other Democrats have taken a softer stance, while still criticizing the GOP tactics.

“I’m not going to reject working with them, or at least considering what they put forward,” said Sen. Dick Durbin Richard (Dick) Joseph DurbinFeinstein 'surprised and taken aback' by suggestion she's not up for Supreme Court fight Grand jury charges no officers in Breonna Taylor death Democrats shoot down talk of expanding Supreme Court MORE (D-Ill.) — who will be Schumer’s No. 2 — while also calling the GOP strategy a mistake.

Spending deadlines

Lawmakers face a pair of spending deadlines within Trump's first 100 days.

The first is a March 16 deadline to raise the debt ceiling, though the Treasury Department could use "extraordinary measures" to extend the deadline.

It will mark the first time Congress will vote to increase the debt ceiling since a 2015 deal brokered between President Obama and then-House Speaker John Boehner John Andrew BoehnerLongtime House parliamentarian to step down Five things we learned from this year's primaries Bad blood between Pelosi, Meadows complicates coronavirus talks MORE (R-Ohio).

The House Freedom Caucus, who normally demand any bump be paired with spending cuts, will have to negotiate for the first time with a GOP president.

They could be emboldened by Trump’s decision to pick Rep. Mick Mulvaney for director of the Office of Management and Budget, a move that quickly earned the president-elect criticism from liberals.

The South Carolina Republican, who helped cofound the Freedom Caucus, has railed against increasing the debt ceiling and previously voted against doing so.

The second deadline will come on April 28, when lawmakers will need to pass a government funding bill or risk a government shutdown.

Lawmakers have given little hint about what a spending deal under the Trump administration could look like, but defense hawks are expected to try to increase defense spending potentially through a stand-alone bill.

That move would run into near certain opposition from Senate Democrats, who will want an equal increase in nondefense spending. Senate Republicans need at least eight Democratic votes to clear an appropriations bill.

Miners' benefits

Lawmakers also have until April 28 to extend healthcare for thousands of miners and their families.

The fight caught national attention after Democrats — led by Sen. Joe Manchin Joseph (Joe) ManchinManchin defends Supreme Court candidate Barrett: 'It's awful to bring in religion' The Hill's Morning Report - Sponsored by Facebook - Trump, GOP allies prepare for SCOTUS nomination this week Trump meets with potential Supreme Court pick Amy Coney Barrett at White House MORE (D-W.Va.) — threatened to hold up a government funding bill earlier this month as they pushed for a yearlong extension of benefits.

But Democrats ultimately caved, accepting the four month extension included in the continuing resolution (CR) and pledging to continue the fight in 2017.

Manchin appears to have an ally in McConnell, who told a local reporter this week that lawmakers would return to Washington and work toward a “permanent fix.”

“Their healthcare deserves to be protected,” the Kentucky Republican said. “It's collateral damage from the decline of the coal industry.”

A longer extension was left out of the CR because of opposition in the House. But Manchin is signaling he'll play hardball over a permanent fix next year.

"The House has a lot of things coming over here starting in January that they're going to want,” he said. “They're going to want some things and there's going to have to be cooperation."

Manchin and his West Virginia Sen. Shelley Moore Capito Shelley Wellons Moore CapitoCongress must finish work on popular conservation bill before time runs out Second GOP senator to quarantine after exposure to coronavirus GOP senator to quarantine after coronavirus exposure MORE (R-W.Va.) are also angling for Trump to throw his support behind a long-term fix, which could help smooth passage in the House.