President Barack Obama has nominated Merrick Garland, chief justice of the U.S. Court of Appeals for the District of Columbia, to the U.S. Supreme Court.

The pick ends weeks of speculation, but marks the beginning of what likely will be months of fighting over whether the Senate should confirm the 63-year-old judge for the seat. Senate Majority Leader Mitch McConnell has pledged not to confirm a new justice before the next president takes office—a position he reiterated after Garland's nomination was announced Wednesday.

Obama on Wednesday praised Garland, saying he “brings to his work a spirit of decency, modesty, integrity, even-handedness and excellency.” He said he's earned respect from those on both sides of the aisle. He was confirmed in his current position by a majority of Senate Democrats and Republicans.

Lawmakers will almost certainly spend coming months digging through Garland's judicial record to see where he stands politically. As chief justice of the U.S. Court of Appeals in Washington, Garland, who is viewed as moderate, has been involved in a number of healthcare-related cases, sometimes siding with hospitals and other times with HHS.