WASHINGTON — Just a week into talks to rewrite the North American Free Trade Agreement, President Donald Trump is already threatening to abandon the 23-year-old pact with Canada and Mexico. At a high-profile campaign-style rally in Phoenix on Tuesday night, Trump predicted that the United States would “end up probably terminating” NAFTA “at some point,” though he said he hadn’t made a final decision. “Personally,” Trump said, “I don’t think we can make a deal because we have been so badly taken advantage of.” The president had made the same threat in April but then reversed himself after a pushback from American businesses, especially farm groups, which have benefited from expanded access to the Mexican market resulting from NAFTA. The president’s renewed threat Tuesday reignited such concerns. “Abruptly ending NAFTA could create a string of unintended consequences that need to be carefully considered,” said Ann Wilson, an executive at the Motor & Equipment Manufacturers Association, which represents auto suppliers.