Labour leadership hopeful Jeremy Corbyn has said "we all owe something" to socialist revolutionary Karl Marx as it was claimed militant activists have infiltrated the contest to help the left-winger to win.
Mr Corbyn, who wants to end austerity and re-nationalise the railways and energy industries, told the BBC's Marr Show Marx's writing was "brilliant" and dodged the question when asked directly whether he was a Marxist himself.
After a poll last week showed the backbench MP has a commanding lead in the polls, senior Labour figures have warned of decades in the wilderness and an ABC - "Anyone But Corbyn" - campaign has been mounted against him.
And senior Labour MPs have urged party chiefs to suspend the race after claiming supporters of hard-left, Trotskyite parties are infiltrating the race by paying the £3 voting fee.
Mr Corbyn was questioned on how left-wing his own views were on the BBC show, particularly over his sympathies for Marx.
The Islington North MP told Andrew Marr "even you" have Marxist beliefs, but said he was only aware of young people "excited about politics" rushing to join.
He said: "Marx analysed what was happening in a quite brilliant way. The philosophy around Marx is absolutely fascinating.
"Does it all apply now? Philosophy applies at all times. Do we then take that as a way in which we ensure people have reasonable security in their lives through public ownership of the major monopolies, then I think that is a fair point to look it. It's not unpopular with the public."
Asked whether he regarded himself a Marxist, he said: "That's a very interesting question. I haven't thought about that for a long time.
"I haven't really read as much of Marx as I should have done. A bit but not that much. Marx's transition of history and the analysis of how you go from feudalism to capitalism and move on to a different sarge is fascinating. We all owe something to it. Probably inside you even you do. I think you do."
But he dismissed the idea of large-scale entryism from supporters of Militant Tendency and other far-left parties, saying: "I have said from the beginning I only want people to register as Labour supporters if they're genuinely a Labour supporter and they intend to stay for the longer course."
He added: "The entryism I see is lots of young people who hitherto have not been very excited about politics."
In the interview, he argued New Labour had been "too close to big business" and was "incapable of offering Labour voters and the majority of the electorate a real alternative".
"That was the fundamental problem of the last election," he said, suggesting Ed Miliband's offer was not left-wing enough.
In the show, he was called a "serious politician" by ex-SNP leader Alex Salmond, and as Labour leader he would know where he stands.
Mr Salmond said: "The demonisation - I am quite familiar with - in the metropolitan press gives no idea of his substance. That doesn't mean I agree with him, he's just a substantial politician.
"You'd know where he stood on certain issues. You'd know absolutely you could co-operate as an opposition against the welfare Bill. That when the proposal to waste £100 million on a new generation of nuclear weapons comes up, you'd have a means of co-operation."