On a series of issues, including free trade and foreign military intervention, Trump is effectively running to the left not only of his own party but also of Clinton.

For weeks, Trump has openly praised Sanders, crediting the senator from Vermont for raising questions about the former secretary of state’s judgment on campaign finance, trade and foreign policy. He has also pointed to Sanders’s questioning of Clinton’s qualifications as a sign that the topic is fair game…

The line of attack poses an unusual and vexing challenge for the Democratic front-runner, who has spent months embracing increasingly liberal positions in her primary fight with Sanders. After jockeying to win over voters on the left, the Clinton campaign is now tasked with pinpointing the best way to attack Trump — an ideological moving target who sometimes switches positions within the space of a day — while also reaching out to moderates and disaffected conservatives.

The real estate mogul has sought to develop a clear contrast with Clinton on foreign affairs and international trade, calling for an “America First” policy that simultaneously turns her experience as the nation’s chief diplomat against her while tapping into the anxieties of angry voters worried about being left behind by globalization. In recent days, he has also moved to the left on the minimum wage and tax policy, suggesting that he is willing to alter his positions to benefit the middle class.