Robert De Niro wants you to wear a mask. So do Morgan Freeman and Kathryn Bigelow. The Hollywood stars are fronting a campaign calling on Americans to cover their faces to stop the spread of COVID-19.

The donning of masks has become politicized in the United States, with many Americans refusing to wear them, following initial conflicting advice about their effectiveness.

President Donald Trump finally yielded to pressure and was seen wearing one in public on Saturday for the first time, even after White House staffers tested positive for the virus. His reluctance came as White House experts leading the fight against the virus have recommended wearing face coverings in public to prevent transmission.

As part of the "Mask Up America" campaign, Oscar winner Bigelow has helped produce eight 30-second television ads in which different actors implore Americans to cover their faces. "When you wear a mask, you have my respect," says Freeman in one of the videos.

De Niro, Jamie Foxx and Rosie Perez also offer their voices to the public service campaign. Frequent Trump critic Andrew Cuomo -- the Democratic governor of New York state, where more than 32,000 have died from COVID-19 -- launched the campaign.

The virus -- which is surging in major states such as California, Texas and Florida -- has killed more than 137,000 people and infected more than 3.5 million in the US.