This week President Obama will welcome leaders from more than 40 countries to the nation’s capital for the 2010 Nuclear Security Summit. The goal of the summit is to keep nuclear materials away from the hands of terrorists while also beginning to examine how best to dismantle the store of nuclear arms worldwide.

"The central focus of this nuclear summit is the fact that the single biggest threat to U.S. security -- both short term, medium term and long term -- would be the possibility of a terrorist organization obtaining a nuclear weapon," Obama said to reporters on Sunday.

On the eve of the Summit, the President held a series of meetings with leaders from India, Kazakhstan, South Africa and Pakistan to reiterate the level of importance and resolve the U.S. has on this issue.

"I feel very good at this stage in the degree of commitment and sense of urgency that I've seen from the world leaders so far on this issue," Obama said after a meeting with President Jacob Zuma of South Africa.

Last week, Obama and Russian President Dmitry Medvedev signed a new Strategic Arms Reduction Talks (START) II treaty that calls on Russia and the U.S. to reduce its number of nuclear warheads and long-range missiles by one-third.

Republicans criticized Obama for appearing weak before the country’s enemies by signing this treaty, and so far no Republicans have indicated they intend to vote in favor of its ratification. The treaty needs 67 votes to be ratified by the Senate; however, according to Senator Lamar Alexander (R-TN), a vote on its ratification appears unlikely to make it to the floor this year.

“There's not a chance the treaty will be approved this year,” Alexander said on Fox News Sunday. “I don't think that taking away the ambiguity in our use of nuclear power is going to scare Iran or scare North Korea. I think only resoluteness on the part of the commander in chief will do that.”

Secretary of State Hillary Rodham Clinton went on ABC's This Week to defend Obama and try to assure the American public of the strength and steadfastness of the Administration.

"Let no one be mistaken. The United States will defend ourselves and defend our partners and allies. We intend to sustain that nuclear deterrent by modernizing the existing stockpile. In fact, we have $5 billion in this year's budget going into that very purpose,” Clinton said. “And with this emphasis on our nuclear stockpile and the stewardship program that we are engaged in, that we'll be, you know, stronger than anybody in the world as we always have been with more nuclear weapons than are needed many times over. And so we do not see this as in any way a diminishment of what we are able to do.”

It Starts Again– Appointing a New Justice to the Supreme Court

On Friday, U.S. Supreme Court Justice John Paul Stevens announced that he will retire from the bench after the summer term. In an instant, pundits and politicos were stirred into a frenzy over whom President Obama might appoint to fill the vacancy.

When appointed to the Court by President Gerald Ford in 1975, Stevens was thought to be a moderate conservative. Over the years, Stevens proved to be the liberal voice of the Court and will leave behind a legacy of defending abortion rights, protecting rights for gays and limiting executive power.

“And while we cannot replace Justice Stevens’ experience or wisdom, I will seek someone in the coming weeks with similar qualities -- an independent mind, a record of excellence and integrity, a fierce dedication to the rule of law and a keen understanding of how the law affects the daily lives of the American people,” Obama said at a press conference.

With Justice Steven’s impending retirement, the replacement process begins anew. Much like the selection of now Justice Sonia Sotomayor last year, Republicans have already begun to voice concerns that a nominee who shares Justice Stevens’ views might be nominated. That said, while there are a number of candidates waiting in the wings, the President has not tipped his hand as to who might be next to join the Court.

The Senate Judiciary Committee oversees the confirmation hearings, and Chairman Patrick Leahy (D-VT) and ranking member Jeff Sessions (R-AL) appeared on NBC’s Meet the Press this Sunday to discuss the process and the qualifications they would like and expect to see in Obama’s nominee.

"He [Obama] has made it very clear he's not looking for somebody who'll be there to represent just Democrats or just Republicans but to represent Americans, to give a voice to Americans who are affected, everyday Americans who are affected by court decisions,” Leahy said. "The Constitution says that 51 senators can confirm somebody. It doesn't require 60 senators. I don't think there's going to be any kind of a filibuster...The American people pay us and, and elect us to vote yes or no, not to vote maybe. Every time you have a filibuster, you're saying, ‘I'm not going to vote yes or no, I'm going to vote maybe.’ That's irresponsible."

“The court should interpret the law, not make the law, and should interpret it in a way that's faithful to the Constitution,” Sessions said. “I promise a fair hearing…a nominee that under extraordinary circumstances a filibuster is appropriate to use against him. I hope we do not do that. I voted against Sotomayor, but that was not a filibuster, and I think we'll just see how it plays out. Depends on the quality of the nominee.”