WARREN, Mich. — Joseph R. Biden Jr. tore into President Trump on Wednesday over new revelations from a forthcoming book by the journalist Bob Woodward that the president knowingly minimized the risks of the coronavirus, arguing that Mr. Trump had lied to the American public and put lives in danger.Mr. Biden’s remarks came as part of a broader effort to take on Mr. Trump over protecting American jobs, and to blame the president’s handling of the pandemic for the nation’s plunge into recession this year.“He had the information,” Mr. Biden said during a trip to the critical battleground state of Michigan. “He knew how dangerous it was. And while this deadly disease ripped through our nation, he failed to do his job on purpose. It was a life-and-death betrayal of the American people.”“It’s beyond despicable,” Mr. Biden added, detailing the crises the nation faces as a result of the pandemic that go far beyond the staggering public health costs. “It’s a dereliction of duty. It’s a disgrace.”During an interview with CNN on Wednesday, Mr. Biden used even sharper language to criticize Mr. Trump’s contradictory message about the gravity of the pandemic.“It was all about making sure the stock market didn’t come down, that his wealthy friends didn’t lose any money,” Mr. Biden said. “He waved a white flag. He walked away. He didn’t do a damn thing. Think about it. Think about what he did not do. It’s almost criminal.”In his outdoor speech at the United Auto Workers Region 1 headquarters in Warren, Mich., Mr. Biden assailed the president’s record on the economy, suggesting that Mr. Trump had not kept his promises to American workers on a range of issues. He also lashed his record on matters like job creation and keeping work in the United States rather than letting it move overseas. The remarks represented an effort by Mr. Biden, the former vice president, to turn the focus of the campaign to the economy after weeks of attention on issues of civil unrest and a series of Trump-related controversies.Mr. Biden’s speech was also another display of how he is trying to campaign in person during the pandemic: He spoke in a parking lot, with journalists and a small number of other attendees sitting at a distance in white circles.A number of Mr. Biden’s allies had made clear in recent weeks that they wanted to see him focus more on Mr. Trump’s stewardship of the economy, something Mr. Biden tried to do in scathing terms on Wednesday.“He’s failed our economy and our country,” Mr. Biden said in his speech, in which he made direct appeals to autoworkers.In an interview with Fox 2 Detroit that aired later Wednesday, Mr. Biden also criticized elements of how the North American Free Trade Agreement was carried out under the George W. Bush administration, when asked to respond to scrutiny from the Trump campaign and others over his own support for Nafta.“The Bush administration did not keep its commitment on Nafta, number one, and it was a mistake,” Mr. Biden said. A Biden adviser said that he had not been calling the agreement a mistake, but was referring to other aspects of trade policy under that administration concerning the agreement.Last year, asked on the campaign trail if his support for Nafta had been a mistake, Mr. Biden said he did not regret it.The former vice president, standing in front of a giant American flag and an array of gleaming automobiles, announced plans to change the tax code to discourage moving jobs overseas and to reward companies for investing in domestic production. He also promised to take a series of executive actions to ensure the purchase of American goods in the federal procurement process.Mr. Biden, who has already proposed raising the corporate tax rate to 28 percent from 21 percent, would create a tax penalty aimed at American companies that move jobs to other countries, known as offshoring. The penalty would apply to “profits of any production by a United States company overseas for sales back to the United States,” bumping up the tax rate to nearly 31 percent on those profits.That penalty would effectively serve as a new tax on American companies that make products abroad and sell them back to customers in the United States, but it would not apply to foreign-owned companies that operate in America and import products to sell. Conservative tax experts said on Wednesday that the disparity would disadvantage American corporations and possibly push them to sell their foreign operations to rivals.“These kinds of rules are not going to bring real activity back to the United States,” said George Callas, who was a senior tax counsel for former Speaker Paul D. Ryan, Republican of Wisconsin, and is now a managing director at Steptoe in Washington. Rohit Kumar, a former aide to Senator Mitch McConnell of Kentucky, the majority leader, who is now a principal at PwC in Washington, said that Mr. Biden’s proposals would in isolation “make U.S. multinationals less competitive vis-à-vis their foreign-headquartered competitors.”“It could also create an incentive for U.S. companies to re-domicile in foreign countries,” he added.Mr. Biden’s plan calls for tougher federal rules against so-called inversions, when an American multinational merges with a foreign-owned one in order to shift its headquarters abroad and qualify for different tax treatment. He has previously announced plans to increase the rate on what amounts to a minimum tax on multinational companies’ income, and to apply that minimum to income earned from each individual country that a company earns revenue in. Liberal economists praised the plan, saying it would reduce incentives to move production and profits overseas. They also said Mr. Biden’s efforts could lead to more countries joining forces to impose a standard set of minimum taxes on multinationals in order to stop companies from shifting profits across borders in search of lower tax rates. “Other countries have a thirst for solving these problems too,” said Kimberly Clausing, an economist at Reed College in Portland, Ore., who studies international tax issues, “and international coordination around minimum taxes may be more feasible than we might think.”Mr. Biden would also create a tax credit for companies that make domestic investments, such as revitalizing closed manufacturing plants, upgrading facilities or bringing back production from overseas.Campaign officials said on Wednesday that they did not have an estimate to share of how the plans Mr. Biden announced would increase or decrease federal tax revenues, in total.“Make it in Michigan, make it in America, invest in our communities and the workers in places like Warren,” Mr. Biden said. “That’s what this is about.”At one point, Mr. Biden appeared to mix up the approximate number of military service members who have died of the coronavirus and the number of people in Michigan who have died from it. As he read from notes, he said that 6,000 service members had died of the virus; in fact, the number is seven. Warren, where Mr. Biden spoke, sits in Macomb County, which is associated with white working-class voters who traditionally voted Democratic but embraced Ronald Reagan and, later, Mr. Trump. Mr. Biden has intensified his efforts in recent months to unveil more populist policies aimed at helping American workers. Some major labor unions praised his announcement on Wednesday, including the United Steelworkers. “I don’t accept the defeatist view that the forces of automation and globalization mean we can’t keep good-paying union jobs here in America, and create more of them,” Mr. Biden said. “I don’t buy for one second that the vitality of American manufacturing is a thing of the past.”Representative Andy Levin, Democrat of Michigan, whose district includes parts of Macomb, described the county as a “complete bellwether” and increasingly diverse.“We’ve got to win Macomb County,” he said. “It’s both a symbol of the white working class, but also really about how diverse the working class actually is.”Thomas Kaplan reported from Warren, Katie Glueck from New York and Jim Tankersley from Washington.