About 500 activists marched Monday afternoon in downtown Chicago to protest U.S. trade negotiations with some Latin American and Asian nations.

The march ended at the Hilton Chicago, where delegations from nine countries on Tuesday will begin their eighth round of talks toward what they’re calling the Trans-Pacific Partnership.

President Obama’s administration says U.S. aims in the negotiations are jobs and prosperity for the American people. His team says it’s addressing shortfalls of earlier U.S. pacts, such as the North American Free Trade Agreement.

That’s not convincing critics. “Thousands of workers here in Chicago and all over the Midwest are out of jobs because of trade agreements like NAFTA,” said Tom Balanoff, president of the Service Employees International Union Illinois Council, at a rally before the march.

NAFTA has also “destroyed the livelihoods” of millions of Mexican farmers, Balanoff added. “And what do they tell us in Washington? ‘Let’s keep following those policies.’ ”

The protestors say they will deliver 10,000 postcards to negotiators on Tuesday. The cards urge the United States to make sure any deal protects labor rights, the environment and human rights.

On Wednesday, AIDS activists are planning to protest proposed treaty provisions that would strengthen pharmaceutical patents. The activists say the patents lock in prices for life-saving medications that poor people can’t afford.

The Chicago talks are set to run through September 15. Besides the United States, the nations include Australia, Brunei, Chile, Malaysia, New Zealand, Peru, Singapore and Vietnam.