In his remarks earlier in the day, President Obama had called for the Senate to put politics aside and confirm Garland. Obama praised Garland's collegiality and ability to build consensus, saying "he's shown a rare ability to bring together odd couples."
A Supreme Court nomination, Obama said, is "supposed to be above politics, it has to be, and should stay that way."
McConnell's comments came after a pledge he made last month that the Senate would take no action on the nomination, setting the stage for a political fight. McConnell said Wednesday that the "the decision the Senate made weeks ago remains about a principle, not a person."
"It seems clear President Obama made this nomination not, not with the intent of seeing the nominee confirmed, but in order to politicize it for purposes of the election," McConnell said.
"I believe the overwhelming view of the Republican Conference in the Senate is that this nomination should not be filled, this vacancy should not be filled by this lame duck president," McConnell said.
"The American people are perfectly capable of having their say on this issue, so let's give them a voice. Let's let the American people decide. The Senate will appropriately revisit the matter when it considers the qualifications of the nominee the next president nominates, whoever that might be," McConnell said.
Here are more responses from Capitol Hill, which we'll continue to update:
Capitol Hill Reacts To Supreme Court Nomination
"The American people shouldn't be denied a voice"
Charles Grassley, Senate Judiciary chair
"Today the President has exercised his constitutional authority. A majority of the Senate has decided to fulfill its constitutional role of advice and consent by withholding support for the nomination during a presidential election year, with millions of votes having been cast in highly charged contests. As Vice President Biden previously said, it's a political cauldron to avoid. Judge Bork learned even after being unanimously confirmed for a circuit court judgeship, the confirmation process for the Supreme Court is unlike any other.
It's also important to remember the type of nominee President Obama said he's seeking. He says his nominee will arrive at 'just decisions and fair outcomes' based on the application of 'life experience' to the 'rapidly changing times.' The so-called empathy standard is not an appropriate basis for selecting a Supreme Court nominee.
A lifetime appointment that could dramatically impact individual freedoms and change the direction of the court for at least a generation is too important to get bogged down in politics. The American people shouldn't be denied a voice. Do we want a court that interprets the law, or do we want a court that acts as an unelected super legislature? This year is a tremendous opportunity for our country to have a sincere and honest debate about the role of the Supreme Court in our constitutional system of government."
"This has never been about who the nominee is"
Paul Ryan, House speaker
"This has never been about who the nominee is. It is about a basic principle. Under our Constitution, the president has every right to make this nomination, and the Senate has every right not to confirm a nominee. I fully support Leader McConnell and Chairman Grassley's decision not to move forward with the confirmation process. We should let the American people decide the direction of the court."
"The next President to make the nomination"
John Cornyn, R-Texas, Senate Judiciary member
"The next justice could change the ideological makeup of the Court for a generation, and fundamentally reshape American society in the process.
At this critical juncture in our nation's history, Texans and the American people deserve to have a say in the selection of the next lifetime appointment to the Supreme Court.
The only way to empower the American people and ensure they have a voice is for the next President to make the nomination to fill this vacancy."
"Cooler Heads Will Prevail"
Harry Reid, D-Nev.
"I am optimistic that cooler heads will prevail, and sensible Republicans will provide Judge Garland with the fair treatment that a man of his stature and qualifications deserves. The American people expect their elected leaders to do their jobs. President Obama is performing his Constitutional duty. I hope Senate Republicans will do theirs."
"I will oppose this nomination"
James Inhofe, R-Okla.
Inhofe is one of the seven sitting Republican senators who voted to confirm Garland in 1997.
"It makes the current presidential election all that more important as not only are the next four years in play, but an entire generation of Americans will be impacted by the balance of the court and its rulings. Sens. Barack Obama, Joe Biden, Hillary Clinton, Chuck Schumer and Harry Reid have all made statements that the Senate does not have to confirm presidential nominations in an election year. I will oppose this nomination as I firmly believe we must let the people decide the Supreme Court's future."