“I’m both saddened and furious that the Senate Dems have jumped on the protectionist bandwagon so fully, with all the rhetorical flourish” said Robert Howse, a law professor at New York University who specializes in international trade. “As a matter of policy, none of these measures, on any plausible economic theory, would result in improving the circumstances of U.S. workers, addressing inequality, or the socioeconomic challenges specific to the U.S. heartland.”

But politicians have taken Mr. Trump’s success as evidence that the political wind is blowing in a different direction.

“Anyone that believes that free trade is fair trade, come to West Virginia,” said Senator Joe Manchin, a Democrat from the state.

Senate and House Democrats last month started an effort to highlight the party’s economic policy proposals under the slogan “A Better Deal.” The first round of proposals includes a $15 federal minimum wage, strengthened antitrust enforcement and measures to hold down prices for pharmaceuticals.

The first set of proposals was presented by a group of liberal congressional Democrats. On Wednesday, Mr. Schumer was joined by the more conservative members of his caucus, including Mr. Manchin and Senator Joe Donnelly of Indiana.

One recurring theme: new agencies. On Wednesday, for example, Democrats proposed the creation of a trade prosecutor to pursue complaints about unfair trade practices. The Office of the United States Trade Representative, and the Commerce Department, have similar responsibilities.

“America’s trade policies are not working for many working families and small businesses,” according to the plan’s introduction. “For too long, big corporations have dictated how trade deals and foreign acquisitions are negotiated and the American worker has been left without a seat at the table.”