The comment was made this week at a town hall meeting held by Rep. Paul Broun (R-GA). He acknowledged that there's "frustration with the president" and moved on.

Source: http://www.npr.org/blogs/thetwo-way/2011/02/25/134054078/crowd-laughs-when-congressman-is-asked-whos-going-to-shoot-obama?ft=1&f=1057

Delahunt, Bill DeLauro, Rosa L. Dent, Charles W. Deutch, Theodore E. Diaz-Balart, Lincoln