Mar 16, 2016:

President Obama announced the nomination of Merrick Garland to the Supreme Court. Merrick is currently a Chief Judge on the D.C. Circuit Court.

In the announcement, Obama mentioned that when Merrick was going through his confirmation to the D.C. Circuit Court, Republican Senator Orrin Hatch (at that time chairman of the Senate Judiciary Committee), supported his nomination. Obama also said:

And he [Orrin Hatch] has since said that Judge Garland would be a "consensus nominee" for the Supreme Court who "would be very well supported by all sides," and there would be "no question" Merrick would be confirmed with bipartisan support.

Read a transcript of Obama's announcement here.

Obama Chooses Merrick Garland for Supreme Court | The New York Times

Feb 23, 2016:

Senate majority leader Mitch McConnell said he will not allow a vote on any Obama Supreme Court nominee.

McConnell Says Senate Won't Vote on Obama Court Pick | ABC News

Feb 16, 2016:

At a presidential news conference, an Associated Press reporter asked President Obama about the process of appointing a new U.S. Supreme Court justice.

The Constitution is pretty clear about what is supposed to happen now. When there is a vacancy on the Supreme Court the President of the United States is to nominate someone. The Senate is to consider that nomination, and either they disapprove of that nominee or that nominee is elevated to the Supreme Court. Historically, this has not been viewed as a question. There's no unwritten law that says that it can only be done on off years. That's not in the constitutional text. I'm amused when I hear people that claim to be strict interpreters of the Constitution suddenly reading into it a whole series of provisions that are not there. There is more than enough time for the Senate to consider, in a thoughtful way, the record of a nominee that I present and to make a decision.

We're going to find somebody who is an outstanding legal mind, somebody who cares deeply about our democracy and cares about the rule of law. There is not going to be any particular position on a particular issue that determines whether I nominate them, but I am going to present somebody who indisputably is qualified for the seat, and any fair-minded person, even someone who disagreed with my politics, would say would serve with honor and integrity on the Court.

Part of the problem that we have here is we've almost gotten accustomed to how obstructionist the Senate's become when it comes to nominations. I've got fourteen nominations that have been pending that were unanimously approved by the Judiciary Committee. So, Republicans and Democrats on the Judiciary Committee all agreed that they were well-qualified for the position, and yet we can't get a vote on those individuals. So, in some ways this argument is just an extension of what we've seen in the Senate generally, and not just on judicial nominees.

Watch a video of Obama's response here.

Feb 13, 2016:

U.S. Supreme Court Judge Antonin Scalia died of natural causes while on vacation in Texas setting the stage for a huge political battle over whether President Obama should or should not nominate a successor during this election year.

Scalia's death also adds another dimension to the 2016 election:

• Assuming Obama does not nominate a successor before leaving office on January 20, 2017 (or he nominates but the Senate refuses to confirm), the next president will be responsible for the nomination
• Because the U.S. Senate must confirm a presidential nominee (by a simple majority), the outcome of the 2016 Senate races will have an affect the confirmation

Now that there are only eight justices instead of nine, it's possible that upcoming cases could result in a split decision (4-4). If that happens, the ruling of the lower court stands.

Scalia was the longest serving justice on the U.S. Supreme Court, appointed by President Ronald Reagan in 1986.

Justice Antonin Scalia dead | The Hill

Justice Antonin Scalia's death quickly sparks political battle | CNN

Supreme Court: What happens in case of a tie? | USA Today

President Obama made a statement on Scalia's death, praising him for his many years of service. Regarding a successor, Obama said:

I plan to fulfill my constitutional responsibilities to nominate a successor in due time. There will be plenty of time for me to do so, and for the Senate to fulfill its responsibility to give that person a fair hearing and a timely vote. These are responsibilities that I take seriously, as should everyone. They're bigger than any one party. They are about our democracy. They're about the institution to which Justice Scalia dedicated his professional life, and making sure it continues to function as the beacon of justice that our Founders envisioned.

Source:

Obama, Barack. (February 13, 2016). "Video and Text: President Obama's Statement on Scalia's Death". The New York Times. Retrieved 2016-02-14.

More:

• Nightmare builds for Senate GOP | The Hill
• Conservatives: Court nominee must be stopped at all costs | The Hill
• McConnell and Grassley: Democrats shouldn't rob voters of chance to replace Scalia | The Washington Post
• Reid to GOP: For the good of the country, stop your nakedly partisan obstruction | The Washington Post
• Can Republicans really block Obama's Supreme Court nomination for a year? Probably. | The Washington Post
• After Antonin Scalia's Death, Fierce Battle Lines Emerge | The New York Times
• After Scalia's death, Obama has opening to shift Supreme Court balance | Fox News
• Why Scalia's death could turn the 2016 election upside down | Fox News
• OBAMA: 'I plan to fulfill my constitutional responsibility to nominate a successor' to Scalia 'in due time' | Business Insider