Obama announced his choice at a ceremony in the Rose Garden, with Democratic Senate leaders and allies looking on.
Garland, who had been passed over before, choked back tears, calling the nomination "the greatest honor of my life." He described his grandparents' flight from anti-Semitism in Eastern Europe and his modest upbringing.
He said he viewed a judge's job as a mandate to set aside personal preferences to "follow the law, not make it."
Obama held up Merrick as diligent public servant, highlighting his work leading the investigation into the Oklahoma City bombing. He quoted past praise for Garland from Chief Justice John Roberts and Sen. Orrin Hatch. And he said Garland's talent for bringing together "odd couples" made him a consensus candidate best poised to become an immediate force on the nation's highest court.
The president urged the Republican-led Senate not to let the particularly fierce and partisan political climate quash the nomination of a "serious man."
"This is precisely the time when we should play it straight," Obama said.
Garland was confirmed to the D.C. Circuit in 1997 with backing from a majority in both parties, including seven current Republicans senators.
Sen. Chuck Schumer of New York, the No. 3 Democratic leader, called Garland's selection "a bipartisan choice."
Senate Minority Leader Harry Reid, who spoke to Obama Wednesday morning, said in brief remarks on the Senate floor that Republicans must act on the president's choice. "He's doing his job this morning, they should do theirs," said the Nevada Democrat.
If confirmed, Garland would be expected to align with the more liberal members, but he is not viewed as down-the-line liberal. Particularly on criminal defense and national security cases, he's earned a reputation as centrist, and one of the few Democratic-appointed judges Republicans might have fast-tracked to confirmation — under other circumstances.
But in the current climate, Garland remains a tough sell. Republicans control the Senate, which must confirm any nominee, and GOP leaders want to leave the choice to the next president, denying Obama a chance to alter the ideological balance of the court before he leaves office next January.
Wednesday morning, McConnell cited a June 1992 declaration by Joe Biden -- then a Democratic senator from Delaware, now Obama's vice president -- that as a general practice, Supreme Court nominations ought to be delayed during presidential election years.
“The Senate will continue to observe the Biden Rule so that the American people have a voice in this momentous decision," McConnell said in a statement delivered immediately after Obama introduced Garland as his nominee.
“The American people may well elect a president who decides to nominate Judge Garland for Senate consideration," McConnell said. "The next president may also nominate someone very different. Either way, our view is this: Give the people a voice in the filling of this vacancy."
[NPR Supreme Court correspondent Nina Totenberg said before Obama's announcement that she had learned that Senate Republicans have signaled via “back channels” that they would approve Garland, but only after the general election in November.]
Ahead of Obama's announcement, the Republican Party set up a task force that will orchestrate attack ads, petitions and media outreach. The aim is to bolster Senate Republicans' strategy of denying consideration of Obama's nominee. The party's chairman, Reince Priebus, described it as the GOP's most comprehensive judicial response effort ever.
On the other side, Obama allies have been drafted to run a Democratic effort that will involve liberal groups that hope an Obama nominee could pull the high court's ideological balance to the left. The effort would target states where activists believe Republicans will feel political heat for opposing hearings once Obama announced his nominee.
For Obama, Garland represents a significant departure from his past two Supreme Court choices. In nominating Sonia Sotomayor and Elena Kagan, the president eagerly seized the chance to broaden the court's diversity and rebalance the overwhelming male institution. Sotomayor was the first Hispanic confirmed to the court, Kagan only the fourth woman.
Garland — a white, male jurist with an Ivy League pedigree and career spent largely in the upper echelon of Washington's legal elite — breaks no barriers. At 63 years old, he would be the oldest Supreme Court nominee since Lewis Powell, who was 64 when he was confirmed in late 1971.
Presidents tend to appoint young judges with the hope they will shape the court's direction for as long as possible.
Those factors had, until now, made Garland something of a perpetual bridesmaid, repeatedly on Obama's Supreme Court lists, but never chosen.
But Garland found his moment at time when Democrats are seeking to apply maximum pressure on Republicans. A key part of their strategy is casting Republicans as knee-jerk obstructionists ready to shoot down a nominee that many in their own ranks once considered a consensus candidate. In 2010, Utah Sen. Orrin Hatch called Garland "terrific" and said he could be confirmed "virtually unanimously."
The White House planned to highlight Hatch's past support, as well as other glowing comments about Garland from conservative groups.
A native of Chicago and graduate of Harvard College and Harvard Law School, Garland clerked for two appointees of Republican President Dwight D. Eisenhower — the liberal U.S. Supreme Court Justice William Brennan Jr. and Judge Henry J. Friendly, for whom Chief Justice John Roberts also clerked.
In 1988, he gave up a plush partner's office in a powerhouse law firm to cut his teeth in criminal cases. As an assistant U.S. attorney, he joined the team prosecuting a Reagan White House aide charged with illegal lobbying and did early work on the drug case against then-D.C. Mayor Marion Barry. He held a top-ranking post in the Justice Department when he was dispatched to Oklahoma City the day after the bombing at the federal courthouse to supervise the investigation. The case made his career and his reputation. He oversaw the convictions of Timothy McVeigh and Terry Nichols, and went on to supervise the investigation into Unabomber Ted Kaczynski.
President Bill Clinton first nominated him to the D.C. Circuit in 1995.
His prolonged confirmation process may prove to have prepared him for the one ahead. Garland waited 19 months to win confirmation to the appeals court. Then, as now, one of the main blocking path was Iowa Sen. Charles Grassley, who argued he had no quarrel with Garland's credentials, but a beef with the notion of a Democratic president trying to fill a court he argued had too many seats.