U.S. Rep. Michele Bachmann told Fox News host Greta Van Susteren that Americans who join, support or fight with Islamic State of Iraq and the Levant should lose their U.S. citizenship, and touted her legislation that would bar anyone who does so from returning to the country.

On Monday, Bachmann introduced her “Terrorist Denaturalization and Passport Revocation Act.” Upward of 100 Americans are believed to be fighting with ISIL. Federal authorities say at least a dozen Somali men and three women from Minnesota are among those who have fled the country to fight alongside or aid extremists in the Middle East.

“The FBI … told me yes, there are Minnesotans that are in Syria fighting for the Islamic State. I asked them … if these individuals want to come back to the United States, they have U.S. passports, would be allowed to do so,” Bachmann told Van Susteren. “I was blown away when the FBI told me they could come back into the United States … as many of them have.”

Islamic State's advances and reports of brutality, including the videotaped beheading of two U.S. journalists, have ramped up pressure on Congress to support efforts against the militant group.

Bachmann’s measure would amend existing U.S. law to make becoming a member of, fighting for, or providing material assistance to a designated foreign terrorist organization the equivalent of renouncing U.S. citizenship. The bill is similar to legislation that Texas Sen. Ted Cruz is advocating for in the upper chamber.

The House Intelligence Committee, of which Bachmann is a member, met Monday to discuss ISIL and other international threats.

Piggybacking on Bachmann's bill, Republican U.S. Senate candidate Mike McFadden also called for strict penalties for Americans going abroad to fight with ISIL and like-minded groups.

"It is necessary ... to ensure that trained terrorists do not come back to the United States with the ability to launch terror attacks here at home," McFadden said in a statement.