White House officials said their research showed that making the vaccines more accessible and having local buy-in from doctors and pharmacists was the best way to sway skeptical conservatives to sign up for a shot. They are planning an advertising blitz on television, radio and the internet to target problem areas: young people, people of color and conservatives, an administration official said…

But behind the scenes, there has been a quiet effort to persuade Mr. Trump to get involved. Joe Grogan, the former director of the White House’s Domestic Policy Council, under Mr. Trump, has been working with the Covid Collaborative on addressing vaccine hesitancy among conservatives…

“Having President Trump doing a public service announcement would be very helpful,” Mr. Grogan said. The Biden White House, however, appears split on how effective Mr. Trump’s involvement would really be.