President Barack Obama Tuesday nominated a slate of judges to the Court of Appeals for the District of Columbia, an aggressive move that is likely to spark swift resistance from Senate Republicans who say the court is underworked and does not need additional judges.

Obama announced his plans to fill all three vacancies on the 11-seat appeals court during a morning news conference in the Rose Garden.

The president’s simultaneously nomination of the three judges for the D.C. Circuit, first reported by CQ Roll Call on May 10, sends a strong message that he intends to push for the nominees in a way that he has not lobbied for his other lower-court choices. Obama had never appeared alongside a judicial nominee other than for the Supreme Court, according to advocates.

The D.C. Circuit is widely considered the second-most-powerful court in the nation because of the important national security and administrative law cases it hears. It received its first new judge since 2006 last month when the Senate confirmed Sri Srinivasan, the former principal deputy solicitor general in the Justice Department, in a unanimous vote. Senate Republicans had twice filibustered Obama’s previous choice to the court, Caitlin J. Halligan, whose nomination was withdrawn earlier this year.

Obama nominated Patricia Ann Millett, an appellate attorney in Washington; Cornelia T.L. “Nina” Pillard, a law professor at Georgetown University; and Judge Robert L. Wilkins of the U.S. District Court for the District of Columbia. The Senate confirmed Wilkins to his current post by a voice vote in December 2010.

Millett is a partner at Akin Gump Strauss Hauser & Feld who has served in the appellate section of the Justice Department’s Civil Division and as an assistant to the solicitor general. Pillard began her career at the American Civil Liberties Union before spending five years at the NAACP Legal Defense and Educational Fund. She also served as an assistant to the solicitor general. Wilkins was a leader in the effort to establish the Smithsonian National Museum of African American History and then from 2002 to 2011 was a partner at Venable LLP before his confirmation to the district court.

The announcement drew praise from liberal legal advocacy groups who have complained that Obama has not made judicial nominations enough of a priority.

“The announcement of President Obama’s decision today to nominate three highly qualified individuals to the D.C. Circuit is a watershed moment for this president and the future of this critical court,” said Doug Kendall, president of the Constitutional Accountability Center.

But it is all but certain to draw strong opposition from Senate Republicans who claim the D.C. Circuit is underworked.

Iowa Sen. Charles E. Grassley, the top Republican on the Judiciary Committee, has introduced legislation (S 699) that would reduce the size of the D.C. Circuit by three seats.

The bill would eliminate one of the court’s seats and distribute two others to the Courts of Appeal for the 2nd and 11th circuits, which he argues are busier. The legislation is co-sponsored by all of the other GOP senators on the Judiciary Committee, along with moderate Republican Susan Collins of Maine, spelling potential trouble for Obama’s new nominees.

Grassley on Monday evening had no initial reaction to the nominees, except to say they aren’t needed.

“The only thing that is controversial [about filling the spots] is that you don’t need any more judges there because they’re only working half as hard as the average of other circuits,” he said.

According to statistics from the Administrative Office of the U.S. Courts, the D.C. Circuit had the lowest caseload per authorized judge last year of the 12 circuit courts. But a spokesman for the Administrative Office emphasized that court caseloads tell only a portion of the story and that workload depends often on the kinds of cases that a court hears.

While Grassley’s bill would redistribute two of the court’s seats to the 2nd and 11th circuits, the Judicial Conference, the policy-setting body of the federal courts, has suggested that another court, the 9th Circuit, is the busiest in the nation.

The conference has recommended that the San Francisco-based court receive four new permanent judgeships, a recommendation based on factors including “filings per panel, the mix of cases, the proportion of oral hearings versus submission of briefs, the contributions of senior judges and the geography of the circuit,” according to a spokesman for the federal courts.

Humberto Sanchez and Steven T. Dennis contributed to this report.