As President Barack Obama has intensified his push to appoint circuit judges to the bench, a new study finds that his administration has been one of the worst in recent history when it comes to filling the nation's federal district courts.

Because judicial vacancies have remained "uniquely high" throughout Obama's term, federal district court judges have rarely been more burdened by caseloads than they are now, the study from the Brennan Center for Justice at New York University School of Law concluded.

"Justice delayed due to overworked judges can too often mean justice denied," wrote study author Alicia Bannon, who serves as counsel for the Brennan Center’s Democracy Program. "The ongoing vacancy crisis in the district courts is unprecedented, and judges and litigants are paying the price as dockets grow."

The judges' workload was higher in 2012 than at any point from 1992 to 2007, when considering the number of pending cases per sitting judge, both full-time active judges and part-time senior judges, the study found. And the caseload reached an all-time high in 2009, with annual vacancies averaging significantly higher than those experienced during George W. Bush’s presidency.

There have been more vacancies in so-called judicial emergencies during 2010 to 2012 than for any point in the previous 10 years, the study found. And for the first time since 1992 (as far back as the researcher went), the average number of district court vacancies has been greater than 60 for five straight years, from 2009 to 2013.

The Brennan Center study does not assign blame the White House or the Senate confirmation process for the vacancy crisis, although those two branches have pointed the finger at each other plenty over the past four years. It only urges action.

"These findings demonstrate the urgent need for the President and Senate to act to fill district court vacancies," Bannon wrote. "Indeed, our findings suggest that to fully address the increasing district court workload, more judgeships are required — further highlighting the importance of filling vacant seats now."

Filling vacant seats has proved troubling since 2009. The White House says Senate Republicans are blocking judicial nominations with the use of filibusters and delays on votes. Senate Republicans say Obama has been slow to make nominations for vacancies.

The slowdown could also be caused at the state level before a nominee is ever officially announced by the White House. Senators essentially have a veto power during the confirmation process over nominees from their state.

Russell Wheeler, a Brookings Institution fellow who studies judicial nominations, tried in April to discern who is responsible for the lack of nominees for vacancies. His conclusion: It’s difficult to tell, and there should be more transparency about pre-nomination negotiations that might produce more nominations.

Wheeler found that for the vacancies without nominees, almost half are in states with two Republican senators, and those vacancies are older than those in other states.

"Home-state senators' effective veto over judicial nominees leads to bargaining—how much currently, we outsiders can’t say—between the White House and home state senators to find nominees that the administration favors and that the home state senators are willing to let proceed," Wheeler wrote.

Last month, Obama decided to strike a new, more aggressive tone on the judicial nominations front when he used the Rose Garden to name three lawyers to a key appeals court without any home state senators—the U.S. Court of Appeals for the D.C. Circuit.

Those nominations are working their way through the confirmation process. One nominee, Patricia Millett, a partner at Akin Gump Strauss Hauer & Feld, has a Senate Judiciary Committee hearing July 10.