President Obama nominated three candidates to fill vacancies on the D.C. Circuit Court of Appeals Tuesday morning in a tough Rose Garden speech that sets the stage for a confrontation with Republicans.

In his nomination of law professor Cornelia Pillard, appellate lawyer Patricia Ann Millett, and federal district judge Robert Wilkins, the president called Republicans out for using Senate rules to block many of his previous judicial appointees.

Because of those maneuvers, the president said, his nominees “have taken three times longer to receive confirmation votes than those of my Republican predecessor.”

“This is not about principled opposition; this is about political obstruction,” Obama said. “I recognize that neither party has a perfect track record here. You know, Democrats weren’t completely blameless when I was in the Senate. But what’s happening now is unprecedented.”

“For the good of the American people, it has to stop. Too much of the people’s business is at stake. Our legal framework depends on timely confirmations of judicial nominees,” he said.

Republicans have accused the president of “packing the court” with his nominations to fill the court vacancies.

“It’s hard to imagine the rationale for nominating three judges at once for this court given the many vacant emergency seats across the country, unless your goal is to pack the court to advance a certain policy agenda,” Iowa’s Senator Chuck Grassley said Monday night.

Senate Minority Leader Mitch McConnell accused the president of trying to “pack the D.C. Circuit so it can rubberstamp the president’s big government agenda” last week. Senator Mike Lee of Utah echoed those claims as well, accusing Democrats of supporting Obama’s attempts “to pack the D.C. Circuit with unneeded judges simply in order to advance a partisan agenda.”

The president refuted that claim directly Tuesday.

“Some Republicans recently have suggested that by nominating these three individuals, I’m somehow engaging in—and I’m quoting here—’court packing.’” he said to some laughter. “People laugh, but this is an argument I’ve made, that—for those of you who are familiar with the history of court packing, that involved Franklin Delano Roosevelt trying to add additional seats to the Supreme Court in order to water down and get more support for his political agenda. We’re not adding seats here. We’re trying to fill seats that are already existing.”

Obama also criticized Grassley for a plan he’s proposed to cut the size of the court down—effectively eliminating the vacancies the president is trying to fill. His argument is that the court doesn’t have enough work to do right now.

Obama insisted it’s “obviously a blatant political move.”

“The fact that Republican senators are now pushing a proposal to reduce the number of judges on this independent federal court also makes no sense. When a Republican was president, 11 judges on the D.C. Circuit Court made complete sense,” he said. “Now that a Democrat is president, it apparently doesn’t. Eight is suddenly enough.”

The D.C. Circuit Court is considered one of the most powerful in the country—second to the Supreme Court—because it often takes major cases. Four current Supreme Court Justices served on the D.C. Circuit Court first—Chief Justice John Roberts, and Justices Ruth Bader Ginsburg, Antonin Scalia and Clarence Thomas.

The Senate unanimously confirmed Sri Srinivasan to the D.C. Circuit Court last month. In March, another Obama nominee, Caitlin Halligan, withdrew her nomination after Republicans filibustered her for the second time.