Sen. Frank Lautenberg, the oldest member of the Senate, died this morning of viral pneumonia. The 89-year-old Democrat was the longest-serving senator in New Jersey and the last senator to have served in World War II. Lautenberg had been fighting health problems for years, including stomach cancer, and had announced his plans not to seek reelection in 2014. He returned to the Senate floor in a wheelchair on April 17 to vote in favor of expanding background checks on gun purchases. Republican Gov. Chris Christie will appoint someone to fill the vacancy left by Lautenberg, and Newark Mayor Cory Booker has spoken about running for the Senate in 2014.