Sen. Arlen Specter (D-Pa.) said on Thursday that Rep. Joe Wilson's (R-S.C.) apology for shouting "you lie!" at President Obama during his Wednesday night speech was not "adequate."

Wilson made his outburst after Obama said that his health reform plan would not ensure illegal immigrants. After making the remark, the president glared at the Republican side of the aisle, as did House Speaker Nancy Pelosi (D-Calif.) and Vice President Joe Biden.

The fifth-term senator tweeted:

Rep. Wilson apologized immediately afterward but I don't think that’s adequate.

"This evening I let my emotions get the best of me when listening to the president’s remarks regarding the coverage of illegal immigrants in the health care bill," Wilson said after the speech.

"While I disagree with the president’s statement, my comments were inappropriate and regrettable. I extend sincere apologies to the president for this lack of civility," he added.

Many members of Congress condemned Wilson's disruption following the address.