Donald Trump faces his biggest test

Story highlights

  • David Gergen: Trump showed he can destroy by knocking out 16 other GOP candidates
  • But can Trump construct and lead a GOP ticket that can win? he asks
  • A key test will be his choice of a vice president, Gergen says

David Gergen is a senior political analyst for CNN and has been a White House adviser to four presidents. A graduate of Harvard Law School, he is a professor of public service and co-director of the Center for Public Leadership at the Harvard Kennedy School. Follow him on Twitter: @david_gergen. The opinions expressed in this commentary are his.

(CNN)As his meeting with Republican leaders demonstrated Thursday, Donald Trump is entering a new phase in his quest for the presidency -- one that makes different demands of him as a leader and is perhaps less suited to his natural strengths.

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Donald Trump flip-flops on key platform issues 01:58
The first phase tested him as a brawler, and he was stunningly effective. Whether you like or dislike Trump, you have to hand it to him that he took on 16 other candidates, some far more experienced in politics, and personally knocked most of them out of the ring. He more than proved he can be destructive.
    But he is now moving into a phase where he will be judged less on his ability to campaign than to govern. And governing is about getting other stakeholders to go along with you and your ideas -- not whether you can run them over. Increasingly, voters will ask whether Trump has the judgment, persuasive power and self-discipline to build coalitions behind him. In short, he must prove he can be constructive.
    Thursday was a beginning, and from all reports, Trump handled himself well. In taking a more conciliatory approach and in paying respect to Republican leaders by coming to them -- rather than insisting they come to him -- he appeared genuinely interested in mending fences.
    But face it, the meeting was the easiest of all possible "summits" with House Speaker Paul Ryan, the highest-ranking elected Republican in the country. For different reasons, both men had keen self-interest in moving toward unity.
    The far more important tests of whether Trump has the right stuff to be presidential will come in the weeks ahead. Ryan and other Republicans quite reasonably want to see a change in Trump's tone as well as substance. Trump is obliging so far. He didn't take any shots at Republicans after their meetings, and he has softened his vow to ban all Muslims -- it was a mere "suggestion," he now says.
    But does Trump have the self-discipline to rein himself in, or is the narcissism and bombast -- not to mention the misogyny -- so deeply engrained that he can't help himself? There is plenty of reason to be skeptical. He seems far less suited to mending fences than busting them.
    A second test of whether Trump would be a good president will be his choice of a vice president. That has always been a serious yardstick by which nominees are judged. The early signs are mixed. Some of the names being floated are attractive, such as Sen. Bob Corker of Tennessee, respected on both sides of the aisle.
    But Trump's process of selection seems curiously narrow, relying almost entirely on the few people he trusts. Notably, he has appointed Corey Lewandowski, his political operative, to head up the search. Compare that to the team Barack Obama assembled for his vice presidential selection in 2008: Eric Holder, Caroline Kennedy and Jim Johnson.
    In his landmark book "Presidential Power," scholar Richard Neustadt argued that the most important power a president has is the power to persuade. So far, Trump has persuaded some 10 million voters in Republican primaries to support him.
    But now, to win, he must persuade another 50 million or more Americans of all stripes to stand with him. He cannot win if two-thirds of all women, 80% of all Latinos and more than 85% of African-Americans continue to disapprove of him.
    Voters know he is an effective brawler, but that's not what will matter to them in November. They must now be persuaded he will be a president who will be a constructive force for change. He has six months, starting with Thursday's meetings on Capitol Hill.