Updated: 12 p.m.

Top Democrats are demanding that Rep. Joe Wilson (R-S.C.) apologize on the House floor for screaming, “You lie!— at President Barack Obama during last night’s joint address to Congress and are investigating whether to take further action.

“It’s clear that the Members of our Caucus are quite upset and quite angry,— said Democratic Caucus Chairman John Larson (Conn.). “I think at a minimum everyone thinks that there ought to be an apology, a public apology on the House floor.—

Larson said Members are researching to see what the rules, precedents and traditions are relating to speeches before the Congress before deciding what other action to take.

“It’s an exercise worth going through,— Larson said. “Whether or not it rises to the level of censure is something for the body to determine.—

Wilson issued an apology last night after the remark, which he made when Obama said his plan would not provide health coverage to illegal immigrants.

Speaker Nancy Pelosi (D-Calif.) said Thursday that Wilson’s outburst was “stunning— but that it is “time for us to talk about something else.—

Pelosi said Wilson could have been removed from the chamber under House rules, but Democratic leaders decided against taking action since he did not continue yelling.

Rep. John Lewis (Ga.), a senior Democrat and civil rights icon, said Thursday that an apology was not enough.

“We have to take some action,— he said. “You cannot have a Member of Congress speaking that way about the president on the floor of the House. … We have to send the strongest possible message.—

Lewis said Republican and Democratic leadership should meet to determine what to do next.