President Barack Obama’s nominee to fill one of the vacancies on the powerful appeals court in Washington withdrew Friday, two weeks after the Senate blocked her from a getting a confirmation vote.

The National Rifle Association had opposed New York attorney Caitlin Halligan due to her involvement while Solicitor General for the state of New York in a lawsuit against gun manufacturers. The NRA said she had tried to undermine a federal law which prohibited lawsuits against gun manufacturers in cases involving criminal misuse of firearms.

But Doug Kendall of the Constitutional Accountability Center, a group supporting Halligan, said that “these arguments against Ms. Halligan were largely based on her work as a lawyer for a client -- primarily as the solicitor general of the State of New York. It is always very dangerous to attribute to a lawyer positions taken on behalf of a client; all lawyers are required to represent their clients’ interests zealously, and they violate their ethical obligations if they fail to do so.”

In a vote on March 6, the Senate fell nine votes short of the 60 needed under Senate rules to end debate on Halligan’s nomination. Sen. Lisa Murkowski, R-Alaska, was the only senator to cross party lines and vote to move ahead on Halligan’s nomination.

In a statement released by the White House, Obama said he was "deeply disappointed that even after nearly two and a half years, a minority of Senators continued to block a simple up-or-down vote on her nomination." He called the filibuster "unjustified."

Halligan’s withdrawal spotlighted Republicans’ use of the filibuster to block several of Obama’s nominees, including another appeals court nominee, Goodwin Liu, whom Obama picked to serve on Court of Appeals for the Ninth Circuit. A filibuster threat scuttled Liu’s nomination in 2011.

Ironically, one of the Washington lawyers who supported Halligan’s confirmation was Miguel Estrada, whose confirmation to the same appeals court in Washington was blocked by a Senate Democratic filibuster in 2003.

Halligan, who served as a law clerk to Supreme Court Justice Stephen Breyer, is now general counsel at the Manhattan district attorney’s office.

In a statement Friday, Senate Judiciary Committee chairman Sen. Patrick Leahy, D- Vt., called Halligan “amongst the most qualified judicial nominees I have seen from any administration. It is a shame that narrow, special interests hold such influence that Senate Republicans for two years blocked an up-or-down vote on her confirmation.”

The court on which Halligan would have served if confirmed, the Court of Appeals for the District of Columbia Circuit, is the second most powerful in the federal judiciary because many federal regulations, from environmental rules to labor laws, are decided there.

The D.C. Circuit court “is more important than the Supreme Court because on so many of the issues that go there, they will have the final word,” Leahy said two weeks ago when discussing Halligan’s nomination. “The Supreme Court will never hear all the requests for appeals from the D.C. Circuit.”