WASHINGTON — Rep. Michele Bachmann, R-Minn., is facing a public firestorm over her accusations that the Muslim Brotherhood is infiltrating the federal government and working for "America's demise."

Her attacks, including one directed at Huma Abedin, an aide to Secretary of State Hillary Rodham Clinton, prompted Arizona Sen. John McCain, the 2008 Republican nominee for president, to denounce her Wednesday from the Senate floor.

He defended Abedin and called Bachmann's comments "specious and degrading."

The State Department also weighed in, saying Bachmann's remarks were "vicious and disgusting lies."

Bachmann's public campaign against Islamic influence in American life has been building for weeks, starting with a series of letters to oversight agencies at five federal departments. In them, she requested formal investigations into what she says are "influence operations" by the Brotherhood, an Islamic political organization.

Abedin, a Muslim of Indian and Pakistani heritage, is married to former Rep. Anthony Weiner, D-N.Y., who is Jewish.

Bachmann, a third-term GOP congresswoman, has been challenged to produce specific evidence for her claims. Meanwhile, she's being accused by some of launching a McCarthy-style witch hunt against Muslim Americans.

Despite the backlash, she doubled down on her efforts Wednesday, alleging the Obama administration "appeases our enemies instead of telling the truth about the threats our country faces."

Bachmann long has attracted criticism from the left, but her public campaign against what she calls a "deep penetration" into government circles by Islamic radical groups is being met with denunciations from both sides of the political aisle.

Rep. Keith Ellison, a Minnesota Democrat and the first Muslim in Congress, went on CNN on Tuesday night to fire back at Bachmann just as she was warning of the dangers of the Muslim Brotherhood and the Obama administration in a keynote speech at a Washington summit of Christians United for Israel, a pro-Israel evangelical group.

"This is McCarthyism at its worst," Ellison said Wednesday, referring to the late Sen. Joe McCarthy, whose name became synonymous in the 1950s with his accusations of Communist infiltration in all walks of American life. "This is one of those moments when you can't stay silent," Ellison said.

Bachmann came to national prominence during the 2008 presidential campaign, when she questioned Obama's "anti-American" associations in a television interview with MSNBC host Chris Matthews.

But this is the first time she has questioned the loyalty of a specific individual in Obama's administration, warning that Abedin has "routine access to the secretary and to policymaking."

McCain defended Abedin in personal terms, calling her a "hardworking and loyal servant of our country and our government."

"These attacks on Huma have no logic, no basis and no merit," McCain said. "They need to stop now."

Bachmann's original letters — sent June 13 and cosigned by Republican Reps. Louie Gohmert of Texas, Trent Franks of Arizona, Thomas Rooney of Florida and Lynn Westmoreland of Georgia — all cite research by a group called the Center for Security Policy. The organization was founded by Frank Gaffney, a controversial figure who has feuded with figures of both the left and right, including conservative icon Grover Norquist, who accused him of bigotry.

Gaffney, who writes widely about the threat of Shariah, or Islamic law, in the United States, has said he was an informal foreign-policy consultant in Bachmann's recent presidential bid.