The $1.9 trillion economic stimulus package that President Biden signed shortly after taking office has become both an anchor and a buoy for his re-election campaign.

The American Rescue Plan, which the Biden administration created and Democrats passed in March 2021, has fueled discontent among voters, in sometimes paradoxical ways. Some Americans blame the law, which included direct checks to individuals, for helping to fuel rapid inflation.

Others appear upset that its relief to people, businesses and school districts was short-lived. The Federal Reserve Bank of Dallas reported recently that several business contacts in its district “expressed concern about the winding down of American Rescue Plan Act dollars and whether nonprofits and K-12 schools will be able to sustain certain programs without that funding.”

Polls show that Americans continue to favor Mr. Biden’s opponent, former President Donald J. Trump, on economic issues. Often, they indicate that only relatively small slices of the electorate believe Mr. Biden’s policies have helped them or their family financially.

At the same time, though, the stimulus may be lifting Mr. Biden’s chances for November in ways that pollsters rarely ask about.

Economists say the relief package, along with stimulus measures Mr. Trump signed into law in 2020, has helped accelerate America’s recovery from the pandemic recession. The United States has grown and added jobs in a way that no other wealthy nation has experienced after the pandemic.