MADISON, Wis. -

U.S. Rep. Paul Ryan says the circumstances that led to the purported beheading of a second U.S. journalist by the Islamic State group reflect a weakness of President Barack Obama's foreign policy.

Ryan heard the news Tuesday while taking questions at a luncheon at the Rotary Club of Milwaukee. An organizer told him of news reports saying an Internet video had just been posted purporting to show the beheading of Steven Sotloff.

Ryan said a prayer might be in order and he called for a moment of silence. Then he said one reason groups like the Islamic State have risen so quickly is because of the power vacuum created by the Obama administration's "bad decisions."

He says the U.S. needs a decisive campaign to "finish off" the Islamic State.

Wisconsin Sen. Ron Johnson said the Islamic State extremists reported to have beheaded a second American journalist are evil barbarians who must be defeated.

The Islamic State group released a video Tuesday that appears to show the beheading of Steven Sotloff. If confirmed, it would be the second such video in two weeks after the killing of journalist James Foley.

Johnson said Tuesday's video highlights the need for the U.S. to intervene in the Middle East to stamp out the terrorist group. Johnson spoke from Plymouth, Minnesota, where he is helping fellow Republican and Senate candidate Mike McFadden campaign against Democratic Sen. Al Franken.

McFadden said the U.S. should continue targeted bombings in Iraq and possibly Syria, but wouldn't support a boots-on-the-ground invasion. Johnson didn't specify the intervention he supports.