US authorities intercepted a letter that contained the deadly poison ricin and was bound for Senator Roger Wicker's office, officials said Tuesday, triggering new security concerns a day after the terror attack in Boston. The tainted letter was detected during a routine mail inspection at an off-site facility and did not reach the US Capitol or Wicker's Washington office, a Senate aide said, citing Senate Majority Leader Harry Reid.

The US Senate voted Thursday to begin debate on the most ambitious gun safety legislation in more than a decade, after a bipartisan group of lawmakers agreed to terms on background checks for commercial gun sales. The move, which included 16 Republicans who ignored obstruction tactics by some conservatives in the chamber, sets up crucial votes next week on amendments to the bill, which also stiffens penalties for gun trafficking and boosts school safety. mlm/dw

US senators eager to head home for the congressional recess on Friday launched what could become a legislative all-nighter -- a rare, free-wheeling session known as a "vote-a-rama." For the first time in four years, the 100 members of the Senate will pack the chamber for 10 hours or more, beginning at 3:00 pm Friday, for dozens of back-to-back votes on amendments to the Senate's pending budget resolution.

A Republican senator seeking to block President Barack Obama's pick to lead the CIA over concerns about drone strikes on US soil completed a nearly 13-hour speaking filibuster early Thursday. In a remarkable display highlighting the partisan rift in Washington, Rand Paul led the filibuster of John Brennan's appointment after the White House refused to unequivocally rule out drone strikes on US soil.