(CBS News) WASHINGTON - Former GOP presidential candidate Michele Bachmann and four other conservative members of Congress are charging that people with ties to Muslim extremists have infiltrated the federal government.
Sen. John McCainWednesday, calling them "sinister" and saying they "need to stop."
Huma Abedin, a longtime aide to Secretary of State Hillary Clinton, has been singled out.
The State Department has responded to the allegations with very harsh language, calling Bachmann's charges "vicious and disgusting lies."
Even Bachmann's own former presidential campaign chief, Ed Rollins, said she was being extreme and dishonest.
It's rare for a senator to publicly rebuke members of his own party. But that's just what Arizona's McCain did, saying on the Senate floor, "These attacks have no logic, no basis and no merit, and they need to stop," after the five House Republicans questioned whether Abedin has ties to terrorism.
"When anyone, not least a member of Congress, launches specious and degrading attacks against fellow Americans on the basis of nothing more than fear of who they are and ignorance of what they stand for, it defames the spirit of our nation, and we all grow poorer because of it," McCain continued.
Bachmann, from Minnesota, and the four other representatives sent letters to top intelligence and security officials last week warning that the Muslim Brotherhood, a global religious Islamic movement whose members have been linked to terrorist groups in the past, may have infiltrated the top levels of U.S. government.
They pointed the finger first at Abedin, who is deputy chief of staff to Secretary Clinton and has been one of her closest aides for nearly two decades. Abedin, who was born in the U.S. and is of Pakistani descent, has been described by both Hillary and former President Bill Clinton as a daughter.
But Bachmann and the others wrote, "Huma Abedin has three family members -- her late father, her mother and her brother -- connected to Muslim Brotherhood operatives and/or organizations."
Minnesota's Keith Ellison, the nation's first Muslim congressman, says, "Our country has gone through a McCarthy period. We cannot allow America to go back to another one."
He said the letters reminded him of the 1950s-era witch hunt for Communists in the government, and called Bachmann's evidence misleading and fake.
"It's like a bizarre game of six degrees of separation. She mentions that her father, who has been dead for two decades, knew a guy who knew a guy who knew a guy who was connected to the Muslim brotherhood in some unspecified way!" Ellison said.
Abedin is a 37-year-old new mother who has graced the pages of Vogue. She is married to former New York Rep. Anthony Weiner, who is Jewish and a fierce defender of Israel.
Weiner resigned in disgrace last year after his provocative texts to female supporters were made public.
In this week's People magazine,they have worked hard to repair their marriage. "I'm proud to be married to him," Abedin said.
This isn't the first time that Bachmann has let her suspicions outpace the facts.
Last year, she suggested, falsely, that HPV vaccines might cause mental retardation.
And in 2009, she urged the media to look into the loyalties of her congressional colleagues. "Are they pro-America or anti-America?" she asked. "I think the American people would love to see an expose like that."
CBS News asked all five House members for an interview about the letters they sent, but none agreed.
In a statement, Bachmann did not back down, saying she would "not be silent as this administration appeases our enemies" and saying she wants a full investigation into the Muslim Brotherhood.
To see the Nancy Cordes report, click on the video in the player above.