But at the same time, Mr Abbott's outspoken Queensland backbencher George Christensen was ridiculing both campaigns - including the one backed by his own colleague - in a series of tweets.

Mr Obama was one of many world leaders to phone Mr Abbott following the tragedy. In a statement, the White House said he noted "the Australian public's embrace of #Illridewithyou and the Muslim leaders who have disavowed the actions of the hostage taker" and "praised Australia's rejection of any violence taken in the name of religion and the fear this violence seeks to stoke".

"It's not just tokenistic, I'll Ride With You has been designed to do something, it's been designed to take away focus from radical Islam, there's a whole heap of people who can see that and there's a whole heap of people who can't and that says something about how pervasive political correctness has become in Australia," he told Fairfax Media.

"Either we start talking about this problem and allow a national debate or there's going to be a groundswell of support for some Pauline Hanson-type of person who says we should close down all mosques.

"It won't take too many more incidents like this for the groundswell to rise up and then you'll have the Geert Wilders-type political response. When you bottle up a legitimate frustration or legitimate concern, that's what you trigger and I'm saying lets have the conversation [about] radical Islam rather than people saying 'don't even mention the 'I' word because if you do someone will get bashed up on a bus'."

Queensland Liberal backbencher Ewen Jones, who is good friends with Mr Christensen, said he was reluctant to comment because he did not want to perpetuate his colleague's comments but felt compelled to do so because the views were wrong.

"Actions like that have to be called out otherwise everyone thinks all white Australia is like that," Mr Jones told Fairfax Media. "This isn't about white Australia, this about Australia. This is not about George Christensen or the political class, this is about the country.

"At times like this, I understand it's very hard not to hate and not judge an entire religion and I understand that but you cannot go around making statements like that thinking good will come out of them."