Posed in front of an American flag and a large banner reading "A Future Made in America Phoenix, AZ," Joe Biden told a crowd of assembled workers, supporters and media last December: "American manufacturing is back, folks."

Eight months on, the Phoenix microchip plant – the centerpiece of Biden's $52.7bn US hi-tech manufacturing agenda – is struggling to get online.

The plant's owner Taiwan Semiconductor Manufacturing Company (TSMC), the largest chip maker in the world, has pushed back plans to start manufacturing to 2025, blaming a lack of skilled labor. It is trying to fast-track visas for 500 Taiwanese workers. Unions, meanwhile, are accusing TSMC of inventing the skills shortage as an excuse to hire cheaper, foreign labor. Others point to safety issues at the plant.