President Biden's plan to replace the government’s fleet of 650,000 cars and trucks with electric vehicles assembled in the U.S. by union workers is easier said than done. Why it matters: The populist "Buy American" message sounds good, but the vehicles Biden wants are still several years away and his purchase criteria would require an expensive overhaul of automakers' manufacturing strategies, not to mention a reversal of fortune for labor organizers long stymied by Tesla and other non-union companies.Support safe, smart, sane journalism. Sign up for Axios Newsletters here.Reality check: Right now, not a single model fits the president's criteria: battery-powered, made in America, by union workers. * Tesla produces the vast majority of EVs in the U.S., and all of its models contain at least 55% American-made parts, according to federal data. But Tesla doesn't have a union and CEO Elon Musk has run afoul of federal labor laws. * General Motors' Chevrolet Bolt is the only U.S.-built EV made by union labor. But it's made mostly with parts imported from Korea. Just 24% of the content is considered domestic. * The Nissan Leaf, another popular EV, is made in Tennessee. But the factory is non-union and only 35% of the parts are domestic. "Made in America" itself is confusing, because current rules governing "domestic" content include parts made in both the U.S. and Canada. * Under the American Automobile Labeling Act, passed in 1992, every car requires a label disclosing where the car was assembled, the percentage of equipment from the U.S. and Canada combined, and the country where the engine and transmission were built. * The newly passed US-Mexico-Canada trade agreement adds another layer of rules about the origin of parts.Biden wants to change the whole system of determining whether a federal vehicle is "American." * Today, the government requires federal vehicles to have at least 50 percent of their components made in America, but loopholes allow the most valuable parts like engines or steel to be manufactured elsewhere, Biden told reporters Monday. * He wants a higher threshold and tighter rules that would directly benefit American workers. Be smart: It's all doable, but definitely not within Biden's four-year term in office. * "It just doesn't add up," said Joe Langley, a forecasting analyst for IHS Markit. "The product is still a few years away." * And replacing 650,000 federal vehicles with EVs would require an increase in U.S. investment through the whole supply chain, including electric motors, batteries and vehicles — all of which will take time, Langley said. * Union leaders are glad Biden is focused on the industry's future. "He sees new technology as a way to grow our industry and our economy," a spokesperson for the United Auto Workers told Axios.Some of that investment is already happening. GM, for example, is overhauling several factories to produce electric vehicles in Tennessee and Michigan. Ford will make its upcoming e-Transit van in Missouri. * But GM, Ford and Stellantis (the newly merged FiatChrysler and Peugeot) just recently committed to build more EVs at union factories in Canada. * And Ford is ramping up production of its highly anticipated Mustang Mach-E in Mexico. What to watch: There could be some surprise winners from Biden's plan. * A handful of well-funded EV startups such as Lordstown Motors, Rivian and Workhorse are developing plug-in commercial vehicles like vans and trucks — things that are often needed in government fleets. * "This could put wind in the sails of a lot of new startups," said Langley.Be smart: sign up FREE for the most influential newsletter in America.