Sen. Frank Lautenberg, D-N.J., passed away early Monday morning from viral pneumonia, his office announced. He was 89.

Senator Lautenberg had suffered health problems in late 2012 and announced in February of this year that he would not seek re-election. New Jersey Gov. Chris Christie, a Republican, will appoint a replacement, according to

The senior senator from New Jersey, Lautenberg was the last living senator who served in World War II, his office said in a statement.