This year marked the first year of Donald Trump's presidency and the first time Republicans held a majority in both chambers of Congress in 10 years, but it wasn't an easy year for Republicans.
For the last 365 days Congress has essentially been under a microscope as Republicans made moves to achieve their ambitious agenda, and along the way members were swept up in a whirlwind of legislative battles and scandals that shaped 2017. Here are the top five:
1. Controversial confirmations
Hot off of President Trump's inauguration, senators went straight into a battle over confirmation of his top cabinet picks. Senate Democrats fought fiercely to slow or derail confirmations for Environmental Protection Agency Administrator Scott Pruitt, Education Secretary Betsy DeVos -- the first cabinet secretary to ever be confirmed by a vice-presidential tie-breaking vote -- and Attorney General Jeff Sessions.
On top of contested cabinet picks, the Senate spent months battling over Judge Neil Gorsuch's nomination to fill the Supreme Court appointment left vacant after the death of Justice Antonin Scalia. President Obama nominated Merrick Garland for the post in 2016, but Senate Republicans refused to hold a vote on the nomination until after the election.
Senate Democrats, furious over the Garland fiasco, prepared to mount a filibuster against Gorsuch, prompting Senate Majority Leader Mitch McConnell (R-KY) to use the so-called "nuclear option." That forever changed the rules of the Senate, so that only a simple majority vote is needed to confirm a Supreme Court Justice nominee.
2. Health care
After seven years of vowing to repeal and replace the Affordable Health Care Act -- also known as Obamacare -- Republicans seemed poised to follow through on that promise in 2017. It was the first item on their legislative agenda, and early in the spring House Republicans unveiled a controversial bill designed to replaced the current health law with what they considered a more patient-centered health care system. It took weeks, but eventually House Speaker Paul Ryan (R-WI) was able to get enough Republican votes to pass the bill, but everything gets trickier in the Senate.
Senate Republicans weren't able to maintain their narrow majority when it came to the massive health care legislation. In the end, Republicans weren't able to get enough votes for even the smallest of measures: a "skinny repeal" that would do away with Obamacare and leave the door open for a replacement later.
In a last-ditch effort, Sens. Lindsey Graham (R-SC) and Bill Cassidy (R-LA) introduced their own bill to repeal Obamacare and replace it with a block grant system for states, but that plan failed as well.
While Congress failed in their mission to revamp health care, Trump signed an executive order allowing individuals to join Association Health Plans outside the individual Obamacare exchanges. Experts said the order effectively threw Obamacare into a death spiral by encouraging younger, healthier Americans to seek cheaper insurance outside the Obamacare exchanges, causing premiums to skyrocket.
Later in the year, Republicans were able to repeal the individual mandate, which required Americans to purchase health insurance or pay a fee, in their tax reform bill.
Many Congressional Republicans have expressed a desire to again attempt a health care fix in 2018, but Trump and McConnell have indicated they plan to kick off the year with a bipartisan infrastructure push.
3. Russia investigations
It seemed as if the underlying theme for all of 2017 was the ongoing and ever-growing investigations into Russian involvement in the 2016 elections.
Both the House and Senate intelligence committees launched probes into the matter and called in multiple high profile witnesses to give testimony both publicly and privately.
One of the most widely watched testimonies was that of former FBI Director James Comey, which came shortly after Trump abruptly fired him. Trump publicly claimed to have fired Comey over his mishandling of the FBI's investigation into Hillary Clinton's email server, but Comey said he believed he was really fired because of Trump's unhappiness about the ongoing Russia investigations.
Later, Sessions was called to testify before the Senate Intelligence Committee about undisclosed meetings he had with Russian Foreign Minister Sergey Lavrov. Sessions, who served a Trump campaign surrogate, had previously stated he had not met with any Russians during the campaign. When it was later revealed that Sessions and Lavrov had in fact met at the Mayflower Hotel, Democrats quickly called for Sessions to resign and Republicans admitted that he should clarify his statements and consider recusing himself from all matters related to the Russia probes.
Sessions later did recuse himself, and Special Counsel Robert Mueller was tapped to lead an independent probe. His inquiry led to indictments for Michael Flynn, Trump's former top adviser, and Paul Manafort, Trump's former campaign manager.
4. Sexual misconduct allegations
The #MeToo movement didn't stop outside the doors of Capitol Hill. Several lawmakers were swept up in a slew of sexual harassment allegations involving multiple women. Unlike other sexual misconduct stories that made headlines across the U.S., it was revealed that many victims of sexual harassment in Congress had no feasible route to seek justice and, in fact, several who did take formal action were paid off with taxpayer dollars.
The revelations toppled several lawmakers, including Sen. Al Franken (D-MN), Rep. John Conyers (D-MI), Rep. Trent Franks (R-AZ) and Rep. Blake Farenthold (R-TX).
Lawmakers introduced bipartisan and bicameral legislation to overhaul the system for reporting harassment in the Capitol and mandating sexual harassment for all members and staffers.
5. Tax reform
Congress' greatest legislative achievement of 2017 came at the tail end of the year when Republicans pushed through a massive, $1.5 trillion tax cut package.
Republicans muscled through the first comprehensive tax reform bill since the one passed during the Reagan administration, in 1986.
The bill lowered the corporate tax rate significantly and provided tax cuts across all income brackets, but it didn't quite live up to the simple postcard tax return Paul Ryan pitched for years.
Passage of the bill -- which was widely unpopular, according to dozens of public opinion polls -- helped Congress end 2017 on a high note and showed that Congressional Republicans could finally come together to pass major legislation and govern after scrambling for the majority of the year to get their caucus on the same page.
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