He explained, defended and played down controversial remarks on Chinese investment and the possibility of the US defaulting on loans, and then refused to be drawn on one of his favourite topics: climate change.

''That is a very good question for [climate spokesman] Greg Hunt,'' Senator Joyce said, with only a touch of amusement at one-upping his interviewer. ''I'm a very responsible person and I'm not going to go into Greg Hunt's portfolio.''

Opposition Leader Tony Abbott lectured his frontbench about discipline on Friday, and shadow treasurer Joe Hockey slapped down Senator Joyce.

Mr Abbott said yesterday: ''Barnaby will always be an authentic and original politician, but I think he got the message loud and clear on Friday that he is now part of the team and that means not running off on tangents … He is a smart politician and I am confident that he is going to learn fast.''

Senator Joyce rejected a newspaper article that said his views on foreign investment, the possibility of the US defaulting and climate change were an echo of the extreme right-wing group the Citizens Electoral Council, which said Senator Joyce was on its mailing list. ''If I'm on the party's mailing list, I can honestly say I can never remember reading anything from them,'' he told the ABC.

The article was obviously bringing him grief. ''Jewish groups are now worried about me and it's just so absurd.''

On his attacks on Chinese sovereign investment in Australian resources, Senator Joyce said he had not called for a ban. As for the ''remote'' possibility of the US defaulting on loans, he cited several sources, including a couple of professors, to back his comment.

Asked whether he accepted he had to curb his commentary now he was shadow finance spokesman, Senator Joyce said: ''Of course I do.''

Asked also if he accepted he had made some mistakes, he said: ''I accept that when people bring up things you've said before, it can cause problems.'' Reverting to the old Barnaby, he added: ''There you go. What's my penance? Three Hail Marys?''