Donald Trump has used a major economic policy speech to portray US presidential rival Hillary Clinton as two-faced on the Trans-Pacific Partnership mega trade deal with Australia, New Zealand and other key Pacific rim nations.
The real estate mogul and former reality TV star said Clinton might publicly oppose the TPP ahead of the November election, but she would change her stance if she became president.
"She supports the Trans-Pacific Partnership - not now but very soon if she wins and we can't let her win," Trump, speaking at the Detroit Economic Club on Monday, said.
Clinton, while secretary of state during US President Barack Obama's first term, supported the TPP, declaring in a speech in Adelaide during her 2012 Australian tour the "TPP sets the gold standard in trade agreements to open free, transparent, fair trade".
The proposed 12-nation TPP involves the US, Australia, New Zealand, Singapore, Japan, Canada, Brunei, Chile, Malaysia, Mexico, Peru and Vietnam.
"A vote for Hillary Clinton is a vote for TPP," Trump said.
Obama signalled last week he would attempt to push the TPP through during the "lame duck" period of his presidency - the weeks after the election and before he leaves office in January.
Trump told his Detroit audience the TPP would be catastrophic for the US automobile manufacturing industry.
Trump's address follows a poor week where he slipped dramatically in the polls after criticising the family of a Muslim-American soldier killed in Iraq and failed to initially support fellow senior Republicans, House Speaker Paul Ryan and Senator John McCain.
In his economic plan, Trump proposed: tax-exempt child care expenses; abolishing the death tax; an end to the estate tax; a 15 percent cap on all business income tax; and the introduction of just three tax brackets.
Trump also accused China of currency cheating, product dumping and "having no real environmental or labour protections".
"China is responsible for nearly half of our entire trade deficit," Trump said.
"They break the rules in every way imaginable, including militarily.
"China engages in illegal export subsidies, prohibited currency manipulation and rampant theft of intellectual property."