Addressing a crowd of 500 people in Sydney, which included "old friends" former prime ministers Bob Hawke and John Howard, the high-profile Republican said America needed its Aussie mate more than ever, even though there might be misgivings about President Donald Trump.
Mr. McCain, who was in Australia to discuss Asia-Pacific security issues, said Russian President Vladimir Putin was the "premier" challenge to American security.
McCain said he plans to introduce a bill that would significantly increase funding for America's military when he returns from his trip.
John McCain (R-Ariz.) said he is disturbed by recent media reports suggesting President Donald Trump's son-in-law Jared Kushner had proposed the creation of a secret backchannel in which the Trump transition team could converse with Moscow. What I would say is that the new administration is just that - new.
Republican McCain - one of US President Trump's most outspoken critics in his own party - said Russia's alleged meddling in elections was a danger to democracy.
Appearing on the ABC's 7.30, McCain called Russia's attempts to destroy "the very fundamental of democracy" by intervening in the United States and French elections, "the far greatest challenge that we have".
"I do believe that most of the time he accepts their advice and counsel".
"So I would urge you to keep at it and hopefully someday in the future under different circumstances America will decide to join you".
Although there has been no evidence to back up the claims that the Kremlin altered the election results, McCain, who is chairman of the U.S. Senate Armed Services Committee, believes Russian Federation was still trying to affect the outcome. "I don't think it's standard procedure prior to the inauguration of the president of the U.S.by someone who is not in an appointed position. It is that very irrational Russophobia that we often talk about", Mezhuyev said.
Asked about the fact Trump had not committed to stay in the Paris climate agreement, McCain said that European leaders were "legitimately concerned" that the United States may pull out. "Yes, it bothers me", he said on Australian Broadcasting Corporation's 7:30 program Monday.
"I'd also point out that Barack Obama made that agreement without an agreement from the Congress of the USA, which then allows this President to revoke it".