UPDATE 11:43 a.m. ET: President Barack Obama nominated Judge Merrick Garland, citing bipartisan respect in the past, to fill the vacancy on the U.S. Supreme Court left by the death to Justice Antonin Scalia.

Garland, 63, is the chief  judge of the U.S. Court of Appeals for the District of Columbia Circuit, where he has served since 1997.

“I said I would take this process seriously and I did. I chose a serious man and an exemplary judge,” Obama said standing next to Garland in the Rose Garden Wednesday morning. “To find someone who just about everyone not only respects, but genuinely likes—that is rare.”

Judge Merrick B. Garland speaks after being nominated to the US Supreme Court as U.S. President Barack Obama looks on, in the Rose Garden at the White House, March 16, 2016 in Washington, DC. Garland currently serves as the chief judge on the United States Court of Appeals for the District of Columbia Circuit, and if confirmed by the US Senate, would replace Antonin Scalia who died suddenly last month. (Chip Somodevilla/Getty Images)

Judge Merrick B. Garland speaks after being nominated to the US Supreme Court as U.S. President Barack Obama looks on, in the Rose Garden at the White House, March 16, 2016 in Washington, DC. Garland currently serves as the chief judge on the United States Court of Appeals for the District of Columbia Circuit, and if confirmed by the US Senate, would replace Antonin Scalia who died suddenly last month. (Chip Somodevilla/Getty Images)

Senate Republicans have vowed to block any nominee Obama puts forward, preferring to let voters choose the kind of justice who will replace Scalia through the 2016 presidential elections.

Garland comes in with a mixed record and will likely face scrutiny from Republicans about his stance on the Second Amendment.

As a Justice Department attorney in the 1990s, he assisted in the high profile prosecutions of Oklahoma City bomber Timothy McVeigh and Unabomber Ted Kaczynski.

President Bill Clinton named Garland to the D.C. Circuit Court in 1997 and he was confirmed by a bipartisan vote in the Senate.

“Fidelity to the constitution and the law has been the cornerstone of my professional life and it is the hallmark of the kind of judge I have tried to be for the past 18 years,” Garland said Tuesday in the Rose Garden. “If the Senate sees fit to confirm me to the position for which I have been nominated today, I promise to continue on that course. Mr. president, it’s a great privilege to be nominated by a fellow Chicagoan.”

In the D.C. vs. Heller gun case, which eventually made it to the Supreme Court, a three-judge panel of the D.C. Circuit struck down most of the Washington, D.C., handgun ban. However, Garland joined Judge David Tatel in voting to have the full court reconsider the decision. Garland and Tatel were on the losing side when the Supreme Court recognized the individual right to bear arms in the Heller case and struck down the district’s ban.

“There is no freedom more fundamental than the right to defend one’s life and family,” said Erich Pratt, executive director of the Gun Owners of America. “The Heller and McDonald decisions are hanging by a thread, as both were decided by 5-4 majorities. If Garland were confirmed, we can expect to see more gun registration, more gun bans, more limitations on ammunition, and all of it would be approved by the Supreme Court.”

In a National Review piece, Carrie Severino, chief counsel for the Judicial Crisis Network, also wrote about Garland voting to uphold an executive action by President Clinton to establish what some considered a de facto gun registration requirement.

But Garland has a long record, and, among other things, it leads to the conclusion that he would vote to reverse one of Justice Scalia’s most important opinions, D.C. vs. Heller, which affirmed that the Second Amendment confers an individual right to keep and bear arms. Back in 2007, Judge Garland voted to undo a D.C. Circuit court decision striking down one of the most restrictive gun laws in the nation. The liberal District of Columbia government had passed a ban on individual handgun possession, which even prohibited guns kept in one’s own house for self-defense. A three-judge panel struck down the ban, but Judge Garland wanted to reconsider that ruling. He voted with Judge David Tatel, one of the most liberal judges on that court. As Dave Kopel observed at the time, the “[t]he Tatel and Garland votes were no surprise, since they had earlier signaled their strong hostility to gun owner rights” in a previous case. Had Garland and Tatel won that vote, there’s a good chance that the Supreme Court wouldn’t have had a chance to protect the individual right to bear arms for several more years …

Garland thought all of these regulations were legal, which tells us two things. First, it tells us that he has a very liberal view of gun rights, since he apparently wanted to undo a key court victory protecting them. Second, it tells us that he’s willing to uphold executive actions that violate the rights of gun owners. That’s not so moderate, is it?

Garland does have a somewhat centrist record, siding with the Bush administration in a key terror case. In 2003, he joined an opinion on the D.C. Circuit prohibiting Guantanamo Bay prisoners from challenging their detention from appealing in civilian courts. The Supreme Court, in 2008, overturned this ruling in the case of Rasul v. Bush.

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Senate Majority Leader Mitch McConnell (R-Ky.) said the choice should be up to the voters, and without speaking no ill of Garland, said: “This is not about the person. It is about the principle.”

Obama said he is doing his job in nominating a justice and called on the Senate and insisted that Republicans in the Senate give Garland a hearing and a vote.

“Presidents don’t stop working in the final year of their term,” Obama said. “Neither should a Senator.”