In a one-line statement, the panel on Thursday evening announced it is “investigating and gathering additional information concerning matters related to allegations” against Massa (D-N.Y.).
Massa, a cancer survivor, announced Wednesday afternoon that he would not seek reelection because he is once again battling the disease.
Allegations also surfaced Wednesday that he sexually harassed a male staffer, but Massa denied the charges.
Massa, who is married with two children, was elected to office in November 2008.
This story was updated at 10:46 p.m.