Finance Minister Mathias Cormann met libertarian groups that are now playing a major role in the United States government shutdown and potential default during a three-week overseas study tour.

Senator Cormann's last meeting in Washington during a 2011 trip was with Grover Norquist, the prominent president of the Americans for Tax Reform, which asks political candidates to put in writing that they will oppose ''any and all tax increases''. Mr Norquist is also a board member of the National Rifle Association.

Senator Cormann also met six members of the Heritage Foundation, a tax-exempt think tank. The foundation's political offshoot, Heritage Action for America, has guided efforts to withdraw funding on US President Barack Obama's flagship healthcare policy, the Affordable Care Act.

Senator Cormann then met Matt Kibbe and Wayne Brough, of the Tea Party group Freedom Works.

A recent New York Times piece detailed how shortly after President Obama won a second term, dozens of conservative activists agreed on a blueprint to defund ObamaCare, as it is known, by cutting off financing for the federal government.