Washington CNN  — 

Scott Walker will offer his foreign policy vision in a speech Friday mostly by contrasting it with what he terms a “retreat” from the world stage by the Obama White House.

“With all of the challenges we face around the globe today, now is not the time for untested leadership. I have been tested like no other candidate in this race,” the Wisconsin governor will say, according to excerpts released early Friday morning. “As President, I will send the following message: the retreat is over.”

The speech at The Citadel in Charleston, South Carolina, gives Walker, who has fairly limited foreign policy experience and has raised some eyebrows with prior comments, a chance to shore up any nagging doubts. Walker will chastise President Barack Obama for misunderstanding Iran’s relationship with ISIS and, more broadly, displaying a passivity and false hope that the world will order itself without American leadership.

READ: Walker hits back at Rubio over whether a governor can be ready for presidency

“We’ve had enough of a President who proclaims that the greatest threat to future generations is climate change,” Walker will say. “We are at war with radical Islamic terrorism. It will not go away overnight. This is a generational struggle. And these radical groups will continue to grow if we do not destroy them.”

Walker will speak on foreign policy about a 15-minute drive away from Marco Rubio, who will be sharing his own vision at nearly the exact same time, also in Charleston.

READ: Rubio takes on China in op-ed ahead of foreign policy speech