It’s best not to get too excited about occasional outbreaks of decency in the Republican Party, because they tend to be short-lived.

Last week, it seemed for a moment that Michele Bachmann had finally gone too far. After she and four other congressmen demanded that the government investigate State Department Deputy Chief of Staff Huma Abedin, a widely respected aide to Hillary Clinton, for ties to the Muslim Brotherhood, prominent Republicans stepped forward to denounce her. “These attacks on Huma have no logic, no basis and no merit,” John McCain said in an impassioned speech on the Senate floor. Noting Abedin’s “sterling character,” House Speaker John Boehner said, “I think accusations like this being thrown around are pretty dangerous.” Ed Rollins, Bachmann’s former campaign manager, unloaded in a column on FoxNews.com: “Having worked for Congressman Bachmann’s campaign for president, I am fully aware that she sometimes has difficulty with her facts, but this is downright vicious and reaches the late Senator Joe McCarthy level.”

This all looked like a sign that even in today’s GOP, there is such a thing as too crazy. “How Michele Bachmann finally jumped the shark,” said a headline on The Washington Post’s The Fix blog.

Reports of Bachmann’s irrelevance, though, were premature. As it turns out, there’s still a big constituency for her conspiracy theories in conservative circles. That’s probably why House Majority Leader Eric Cantor came to Bachmann’s defense on Friday morning. Asked by Charlie Rose whether she was “out of line,” he simply said, “I think that her concern was about the security of the country.” Who could fault her for that?

Cantor’s words demonstrated the power of the conservative backlash against Bachmann’s critics. She may be a joke in the Beltway, but she remains immensely popular with the right-wing grassroots. Having collected $14.8 million in donations this cycle, she’s the second-biggest fundraiser in the House, behind only Boehner. She speaks for an important chunk of the Republican Party, and the Tea Party, the Christian right, and conservative talk radio are all rallying around her.

“John McCain needs to sit down and shut up,” said Judson Phillips, head of Tea Party Nation, in an email blast headlined “Michele Bachmann and the battle for the truth.” The Family Research Council lauded her for asking the “tough questions,” saying, “Like us, she believes the business of national security shouldn’t be driven by political correctness. It requires careful scrutiny, vigorous debate, and fearless leadership—three things on which Rep. Bachmann will not compromise.” Sean Hannity called Bachmann and her four congressional colleagues “modern day Paul Reveres.” Christian radio host Steve Deace tweeted, “Grassroots patriots: want to know who’s at least somewhat on your side? Look at their response to Michele Bachmann controversy. Litmus Test.”

On Tuesday, Bachmann was even defended by one of Mitt Romney’s most prominent foreign policy advisers, hyper-hawk John Bolton. “What is wrong with raising the question? Why isn’t even asking whether we’re living up to our standards a legitimate level of congressional oversight?” he asked on Frank Gaffney’s radio show. (Gaffney, a former Bachmann adviser, is a longtime font of conspiracy theories about Muslim Brotherhood infiltration.)

Someone should ask Romney whether he agrees with Bolton and Cantor and thinks Bachmann’s queries about Abedin are legitimate. Chances are, even if he doesn’t, he won’t say so too loudly.