Jim Molan in the Senate on Wednesday. Credit:AAP Britain First are part of the global network of white supremacist and neo-fascist groups emboldened by the election of Donald Trump and the so-called "alt-right" movement which helped spring him into power. Just like the Islamic terrorists they claim to be fighting against, their aim is revolutionary political and social change, they use the internet to radicalise followers, and they are loosely connected through interdependent cells, sharing resources and tactics across the internet. They incite and inspire real violence against real people. They are an utterly rotten lot to lie down with, even in a loose "I just posted it to Facebook to provoke debate"-kinda way.

And yet Senator Molan fumbled his last step in the dance - he didn't apologise for endorsing the extremist group. Far from it, he doubled down, telling Sky News he had been "unwise" not to "clean" his social media, but "the reason that I didn't do that is because I saw nothing wrong with that". "Call me naive but I didn't know that Britain First was the kind of organisation that on occasion it has proven to be," he said. On Thursday night he told 7.30: "I believe a year ago I did nothing wrong." Molan is a decorated former major-general who was appointed chief of operations for coalition forces in Iraq in 2004.

He immediately raised his distinguished record as a means of attacking his detractors. "I put my life on the line for Islamic countries," he said. "For people to come out now and say that this is racist, or is anti-Islamic, I find deeply offensive." It is a general rule in politics that the bigger the mis-step, the greater the moral umbrage used to deflect criticism. Following Molan's lead, Prime Minister Malcolm Turnbull nakedly deployed this technique during Question Time, when the opposition called upon him to rebuke his new senator over the videos.

"That is deplorable," frothed the Prime Minister. "It is disgusting!" But it was perfectly reasonable to expect a moderate Liberal prime minister, a man committed to tolerance and social cohesion, to distance his government formally from the lunacy and hatred of the far-right. What is deplorable and disgusting is the way such groups consistently hack away at the middle ground of Western political debate in order to normalise ideas previously considered too wacky to be acceptable. Much has been written about this strategy in the United States, where the rise of the so-called alt-right has transformed the face of mainstream politics to the extent that blatant propaganda, conspiracy theories and Nazism are now regular features of political debate. The far-right groups have achieved this by re-framing the debate, or widening what has been dubbed the "Overton Window" (named after think-tank executive James P Overton, who came up with the idea).

The Overton Window is the spectrum of things considered acceptable within public debate, the suite of policies or ideas a politician can safely embrace in order to get elected. The goal of activists from the left or the right fringes is to shift the Overton Window and bring previously inconceivable ideas (gay marriage, votes for women, a self-confessed sexual assaulter as president) into the respectable mainstream. The far-right groups in the United States are openly pragmatic about making sure they "pass" as respectable, so they are not discounted as unwashed, unhinged weirdos who exist outside the bounds of polite society. American alt-right leader and white supremacist Richard Spencer has said of his movement: "We have to look good". Spencer says middle-class whites will be turned off a group that appears "crazed or ugly or vicious or just stupid", full of "redneck, tattooed, illiterate, no-teeth [people]".

What has all that got to do with Senator Molan? The far-right movement could not ask for a better or more respectable front than the office of a Liberal senator with an honourable record of military service. If you believe that the extreme-right will never be able to weasel its way into the political mainstream in Australia like it has in the United States, remember this: last year we had a serious debate about the mass internment of terrorism suspects, which is to say, Muslim people who have not been convicted of any crime. Who kicked it off? Pauline Hanson, and one Jim Molan, who wrote a piece for the Herald-Sun suggesting internment of people on terror "watchlists". Molan admitted internment had "a very dirty back-story" but suggested terror suspects could be warned and then put before a tribunal "consisting perhaps of a judge but also of non-jurists" before being interned without trial.

He predicted that "well-intentioned and principled people will fight the sacrifice of more rights, until of course their children are killed at a rock concert or in a bar". Molan said this week he is "anti-violence and anti-civil disturbance". It is his duty as a parliamentarian to guard staunchly the borders of civil debate. Loading Twitter: @JacquelineMaley