President Barack Obama is nominating Merrick Garland to the U.S. Supreme Court, the AP reports.
Garland, 63, is currently the Chief Judge of the United States Court of Appeals for the District of Columbia Circuit.
Bill Clinton nominated Garland to the post in 1997.
Several Senate Republicans have stated they will block any nomination Obama makes.
According to the AP, the president wrote in an email that he devoted "considerable amount of time and deliberation to this decision" and consulted with experts.
"In putting forward a nominee today, I am fulfilling my constitutional duty. I'm doing my job," Obama wrote. "I hope that our senators will do their jobs, and move quickly to consider my nominee."
Sen. John McCain said in a statement that it is not appropriate for Obama to make a nomination because it's an election year.
"This issue is not about any single nominee - it's about the integrity of the Court. With less than a year left in a lame-duck presidency and the long-term ideological balance of the Supreme Court at stake, I believe the American people must have a voice in the direction of the Supreme Court by electing a new president," McCain said. "The last time the American people spoke, they elected a Republican majority to the Senate to act as a 'check and balance' on President Obama's liberal agenda - a responsibility I cannot ignore. We must allow the people to play a role in selecting the next lifetime appointment to the Supreme Court."