“We’re about to turn things around in a big way,” Mr. Biden said in remarks at a bridge over the Pemigewasset River, in snowy New Hampshire. “For example, because of this law, next year will be the first year in 20 years that American infrastructure investment will grow faster than China’s.”

The president has cast the legislation as a giant leap for the United States in its battle with China to dominate the 21st-century economy, even though it does not include the full scope of his campaign promises to pour money into research and development and provide incentives for domestic manufacturing and other initiatives.

“It’s an important step, although it’s not a huge one, if one thinks about the progress China has made in building up its physical and soft infrastructure,” said Eswar S. Prasad, an economist at Cornell University who specializes in trade policy. The infrastructure law “is a good defensive measure,” he added. “But will it fundamentally alter the dynamics? Not by itself.”