Janet Yellen, the first woman to be nominated to head the Federal Reserve. (Eugene Hoshiko/AP Photo)

The landmark Senate vote to effectively eliminate the filibuster of presidential nominees opens the door to a wave of likely confirmations for President Obama.

Gone are the days when 60 votes are needed to move ahead on a nominee. Now, a simple majority of 51 votes is all it takes for confirmation. Here's a list of key Obama administration appointees who stand to benefit the most from last week's historic Senate rules change.

The Three D.C. Circuit Court Nominees

Republican senators, led by Senate Judiciary Committee ranking member Sen. Chuck Grassley, R-Iowa, have been trying to prevent President Obama's three nominees from being confirmed to the nation's second-highest court.

Republicans have said that the D.C. Circuit has a rapidly decreasing caseload and that President Obama has been trying to "pack" the court by filling these vacancies. This is in contrast to previous Republican criticisms of some of President Obama's judicial nominees, which have largely focused on their qualifications and judicial temperament (including previous nominee Caitlin Halligan), rather than the seats themselves to which they were nominated.

Without a 60-vote threshold needed for confirmation, it's likely that nominees Patricia Millett, Cornelia Pillard and Robert Wilkins will be confirmed to the powerful court.

Mel Watt

Rep. Mel Watt, D-N.C., is the second of President Obama's nominees to head the Federal Housing Finance Agency (which supervises Fannie Mae and Freddie Mac) after North Carolina banking regulator Joseph Smith withdrew from consideration. Watt is the only sitting member of Congress to have been filibustered since Reconstruction, Many think that was because Watt would arguably make it easier for homeowners to refinance their home loans, which acting agency head Ed DeMarco has been more reluctant to do.

Jeh Johnson and Alejandro Mayorkas

Johnson and Mayorkas have been nominated to be Secretary and Deputy Secretary of Homeland Security, respectively. Johnson has been criticized by Republicans as merely an Obama bundler and administration cheerleader, though he is also likely to take heat from some Democrats regarding his tenure as the Department of Defense's General Counsel.

Mayorkas, however, may face a bigger hurdle. The current director of the U.S. Citizenship and Immigration Services is under investigation by Homeland Security's Inspector General for his potential, though not confirmed role in helping a company headed by Anthony Rodham (brother of former Secretary of State Hillary Clinton) obtain an international investor visa. Filibuster reform is likely to allow both these nominees to be able to let out a sigh of relief for the time being.

Janet Yellen

Yellen, the first woman nominated to head the Federal Reserve, was never widely believed to be under the threat of a possible filibuster effort. During her vote in the Senate Banking Committee last week, however, Sen. Mike Johanns, R-Neb., who was previously thought to be one of her Republican supporters, voted against her. In addition, Yellen wasn't able to secure the vote of West Virginia Democratic Senator Joe Manchin. Without previous filibuster rules serving as a barrier, it is now more likely than not that Yellen will glide towards confirmation.

Timothy Massad

Massad is Obama's nominee to head the Commodity Futures Trading Commission, which is most widely known as the premier regulator of the derivatives market. Current chair Gary Gensler has taken a relatively aggressive approach to futures and options regulation despite large funding decreases for the agency. Massad's views on derivatives regulation aren't that well known, so he's likely to face at least some scrutiny during his Senate confirmation hearing.

John Koskinen

President Obama chose Koskinen to take over the embattled IRS after reports leaked out that officials in the agency's Cincinnati office placed extra scrutiny on tea party-affiliated groups applying for tax-exempt status. While Koskinen doesn't have any notable blemishes in his record, he will have the tough job of convincing senators that he's the right person needed to turn around an agency that has lost the trust and confidence of many lawmakers and American citizens.

Vivek Murthy

Murthy, President Obama's nominee to be the next Surgeon General, is a physician at the Boston-based Brigham and Women's Hospital, as well founder and president of Doctors for America. Doctors for America is an advocacy group comprising more than 16,000 physicians and medicals students advocating for an improved health care system. The group has largely been supportive of the Affordable Care Act. Though some lawmakers may not be entirely pleased with the policy positions of Murthy or that of his group, it's unlikely that his nomination will be actively derailed since President Obama would not have nominated someone who's opposed to the ACA in the first place.

Debo Adegbile

Adegbile, now a senior counsel to the Senate Judiciary Committee, was recently nominated to be Assistant Attorney General for Civil Rights upon the confirmation of Tom Perez to be Secretary of Labor. A former high ranking official at the NAACP, Adegbile is likely to be a fierce enforcer of voting rights laws as well as an opponent of some state initiatives to change them if he's confirmed to the position. This will not sit well with some GOP senators who are in favor of altering these laws in order to crack down on voting fraud and Adegbile will likely be grilled about this during his hearing. The filibuster rules change will be helpful to Adegbile if his nomination becomes more contentious than it is currently perceived to be.

Henry Aaron

Brookings Institution scholar Henry Aaron was first nominated by President Obama to chair the Social Security Advisory Board back in 2011. The former Carter Administration official has been accused by Republicans of being a proponent of healthcare rationing and his nomination has been stalled in the Senate. At a time when the Affordable Care Act is receiving the most scrutiny since it was first enacted, the Senate rules change may be Aaron's get out of jail free card in getting him confirmed to the influential position.

Ken Kopocis

The former Senate Environment and Public Works Committee staffer is now serving as a senior advisor to EPA Administrator Gina McCarthy while he awaits confirmation to head the EPA's Office of Water. Though Kopocis, who was first nominated in 2011, was voted out of committee largely along party lines, he is thought to have admirers that include EPW Committee Ranking Member, Sen. Jim Inhofe, R-Okla. More so, Kopocis's nomination is being held up at a time when Republicans are very skeptical of the EPA and what they see as the agency's overzealous approach to regulation.