President Biden cautioned in his prime-time address Thursday that it would take a united front among all Americans to defeat the coronavirus pandemic, but the White House is finding it may face an uphill battle convincing those on the other side of the aisle to get vaccinated.

Public polling has shown Republicans are less likely to get the coronavirus vaccine than Democrats. A PBS Newshour/NPR/Marist poll released Thursday found 41 percent of Republicans said they would not get the shot, and a CBS News poll released late last month found 34 percent of Republicans said they will not be vaccinated for COVID-19.

The disparity presents a serious problem for a Democratic administration coming out of a contentious election season, mainly because Biden, Vice President Harris, former President Obama and other high profile Democrats are unlikely to persuade enough conservatives to get the shot.

“We recognize as a Democratic administration with a Democratic president that we may not be the most effective messenger to communicate with hardcore supporters of the former president, and we have to be clear-eyed about that,” White House press secretary Jen Psaki said Friday.

The White House has looked to business groups and religious organizations to urge their constituencies to get the shot when it’s their turn. Personal physicians will play a key role, and entertainers and athletes popular with different demographics could help overcome vaccine hesitancy, experts said.

The National Rural Health Association, the National Farmers Union and the Rural Broadband Association are among the groups the White House has leaned on to reach more traditionally conservative areas of the country, where vaccine access will also be critical.

Francis Collins, head of the National Institutes of Health, has appeared on Christian Broadcasting Network.

Andy Slavitt, a senior adviser to the White House on the pandemic, has appeared on Fox News and Hugh Hewitt’s radio show in recent weeks in a bid to use conservative media to update the public on vaccination efforts. During his Fox hit on Thursday, Slavitt made a point to credit the Trump administration with laying the foundation for the state of the vaccine rollout.

“I do think it’s incumbent upon the Biden administration to ask conservatives to help get white conservatives vaccinated. And I do think there are people in the Biden administration who want to do that,” said Joe Grogan, who served as head of the Domestic Policy Council during the Trump administration and now works with the bipartisan COVID Collaborative, a group working with state and local officials to combat the pandemic.

Experts said it may be too soon to tell which groups are truly the most reluctant to get the shot until there is enough supply to meet demand for the vaccine.

“It’s hard to talk about it in a way because right now it’s really a supply problem, but at some point in the foreseeable future it will become a demand problem,” said Jamie Druckman, a professor at Northwestern University who conducted a survey last year that found mistrust in institutions was one contributing factor to vaccine hesitancy.

“And at that point we’ll be able to have a much clearer picture of: Is it the people who are saying in these surveys they’re vaccine hesitant? Is it a subset of them? Or is it a different group?” he added.

Republicans are far from the only group that has expressed reluctance to get vaccinated. The administration has been adamant about the need to reassure African Americans, Hispanics and other minority communities that the shot is safe, especially since they are hardest hit by the virus. Early data has also shown members of the military and some health care workers are declining the vaccine at concerning rates.

Biden in his prime-time address Thursday urged everyone to do their part to get vaccinated and encourage neighbors and family members to do the same. He pleaded for national unity in fighting the pandemic, but he opened it by dinging former President Trump for his handling of the pandemic.

Trump retains a sizable and fervent base of supporters. But he has appeared uninterested so far in using his platform to combat vaccine hesitancy.

Trump, who espoused conspiracies about vaccines before he took office in 2017 and spoke openly about how he declined to get a flu shot for years, got his coronavirus vaccine days before leaving the White House in January. But he did not do it on camera as Biden, former Vice President Mike Pence and others did, and he has only explicitly urged his supporters to get vaccinated once in a throwaway line during his speech at the Conservative Political Action Conference.

Trump has been eager to take credit for the rapid development of vaccines during his administration. He issued a statement on Wednesday through his post-presidency office, saying “I hope everyone remembers” his role in developing the shot. But experts and former Trump officials say it would make a meaningful difference if the former president did more to try and reduce vaccine hesitancy.

“I think it would be huge if he were to step up,” Grogan said. “I don’t want to speculate as to why he hasn’t yet. He still has a tremendous reservoir of support, and I think a lot of people would respond if he issued a message to get the vaccine.”