MANCHESTER, N.H. — President Trump doubled down on his economic argument for re-election on Thursday night amid increasing concerns about a recession, declaring that even Americans who hate him “have no choice” but to vote for him because otherwise the stock market will collapse.

With markets already wobbling over fears of a slowdown amid an escalating trade and currency war with China, Mr. Trump flew to a battleground state to defend policies that are rattling many businesses and investors and to insist that he will prolong the country’s decade-long economic expansion into a second term.

“You have the best unemployment, you have the most successful state in the history of your state and the history of our country,” he told a campaign rally in Manchester, N.H. “And then you’re going to vote for somebody else? Oh great. ‘Let’s vote for Elizabeth “Pocahontas” Warren. We have the best numbers we’ve ever had — let’s vote for somebody else.’”

Even as he derided Ms. Warren, a senator from next-door Massachusetts and a Democratic presidential candidate, with a racial slur, Mr. Trump acknowledged the deep antipathy many voters have for him but made the argument that they should put aside their distaste for their own economic well-being.