President-elect Donald Trump faces high levels of partisan polarization that will make it difficult to change the views of non-supporters. (Chip Somodevilla/Getty Images)

Public support is a key resource that modern presidents have typically sought for themselves and their policies. They seek to leverage public opinion to garner support in Congress.

New presidents, basking in the glow of victory, often assume that they can move the public. After all, they have just won the biggest prize in American politics because they persuaded enough voters to support their candidacy. Why shouldn’t they be able to persuade Americans to support their policies?

Campaigning is different from governing, however. To win an election, a candidate need only convince voters in the short term that he or she is a better choice than the few available alternatives. In addition, someone always wins, whether or not voters support the victor’s policy positions.

Governing, on the other hand, involves deliberation, negotiation and often compromise over an extended period. The president’s policy is just one of a wide range of alternatives. To succeed, the president frequently needs to increase public support beyond his electoral coalition.

This brings us to Donald Trump. Is President Trump likely to enjoy broad public support to revolutionize public policy? Here are four questions to predict this critical aspect of his presidency.

Did Trump receive a mandate from the people?

It is a great advantage for a president to start his tenure with broad public support. Trump is following a long tradition of new presidents claiming a mandate from the people, a widespread endorsement by the public for a candidate’s policy proposals. The perception of an electoral mandate adds legitimacy and credibility to the new president’s proposals and encourages members of Congress to support the president. Indeed, major changes in policy, as in 1933, 1965 and 1981, rarely occur in the absence of such perceptions. Mandates can be powerful symbols in American politics.

Despite the claims from Trump Tower, however, the president-elect did not receive a mandate. He received only 46 percent of the vote, hardly a landslide. Moreover, he did not win even a plurality of the votes, receiving nearly 3 million fewer than Hillary Clinton.

In addition, pre-election polls found that no candidate since 1980 has had a lower percentage of voters saying they planned to cast a vote for their candidate. In late October, most Trump voters were voting against Hillary Clinton rather than for him. Immediately after the election, 43 percent of the public had a positive response, but 52 percent were upset or dissatisfied.

Approval of his transition has been unusually low, as have expectations of his presidency. The president-elect’s favorability ratings have also been historically low and have not increased during the transition.

Finally, Trump did not emphasize many specific policies during the campaign. Instead, he stressed general aspirations, such as making America great again. So there is little evidence to support claims of a mandate.

The public seems to agree. After the election, just 29 percent said Trump had a mandate to carry out the agenda he presented during the campaign, while 59 percent thought he should compromise with Democrats when they strongly disagreed with the specifics of his policy proposals.

Do Americans support the general direction of Trump’s policies?

To bring about change, presidents generally require broad public support for the general direction of their initiatives. Everyone supports peace and prosperity in campaigns, but presidents have to govern with more specificity. Most Americans like tax cuts (except for the wealthy), rebuilding the nation’s infrastructure and improving veterans’ services.

Trump’s policies often have been unclear, however, and they contain numerous contradictions, such as those between tax cuts and increased spending. We know the public does not support his general approach to immigration, trade and environmental protection. Opinion is more divided on health care, an issue on which he has been especially vague.

How polarized is public opinion?

In the absence of large majorities in Congress, enacting major changes in public policy usually requires expanding public support beyond those who identify with the president’s party. The degree of partisan polarization will influence the prospects of doing so.

Is it possible to reach out to the center and add those who might be sympathetic to Trump’s policies to his coalition? Not really. The United States has very high levels of partisan polarization, and the policy divide between the Democratic and Republican electoral coalitions now encompasses a wide variety of issues, including both economic and social concerns.

Earlier this year, the Pew Research Center found that 45 percent of Republicans said that Democratic policies were not only wrong but “threaten the nation.” Forty-one percent of Democrats viewed GOP policies in equally stark terms.

Trump is highly polarizing, and he has focused on emotionally laden issues such as those dealing with ethnicity, race and gender. Bridging the partisan divide will be one of his greatest challenges.

How malleable is public opinion?

Can the president persuade non-supporters to change their minds and support his initiatives? There are many impediments to leading the public, including:

  • the difficulty of obtaining and maintaining the public’s attention
  • the dependence on the media to reach the public
  • the distrust of the White House created by partisan media
  • the need to overcome the public’s policy and partisan predispositions (which are reinforced by partisan media)
  • the public’s misinformation and resistance to correction
  • the public’s aversion to loss and thus wariness of policy change

Although Trump seems to enjoy an extraordinary rapport with his most enthusiastic supporters, the question is whether he can change the views of those who do not support him. The evidence is clear that his efforts are unlikely to succeed. Indeed, presidents find it difficult even to change the views of their fellow partisans who happen to disagree with them on an issue.

There’s no silver bullet.

President Trump is unlikely to enjoy broad public support. He begins from a weak position and faces a highly polarized public. Moreover, he has little chance of changing many minds, not because he lacks persuasive skill but because of the nature of public opinion. Ronald Reagan, Bill Clinton, George W. Bush and Barack Obama all failed to do so.

Nevertheless, it is critically important for presidents to assess accurately the potential for obtaining public support. Presidents who fail to do so are prone to overreach and political disaster.

George C. Edwards III is University Distinguished Professor of Political Science and Jordan Chair in Presidential Studies at Texas A&M University. He is also a distinguished fellow at the University of Oxford.