Delaware Senate candidate Christine O'Donnell will be in Washington Friday to speak at a major gathering of conservative activists.

O’Donnell was added to the afternoon program at the Values Voter Summit after her surprise victory over Rep. Mike Castle in the Delaware GOP Senate primary on Tuesday.

Her appearance comes as a new poll shows her trailing Democrat Chris Coons by 11 points. Coons took 53 percent of the vote to 42 percent for O'Donnell in a Rasmussen Reports poll out Thursday. Only 4 percent of respondents said they were undecided.

The Sept. 15 survey of 500 likely Delaware voters has a margin of error of plus or minus 4.5 percent.