julian zelizer is a professor of history and public affairs at princeton university and a new america fellow. he is the author of " jimmy carter " and " the fierce urgency of now: lyndon johnson, congress, and the battle for the great society ." the opinions expressed in this commentary are his.









(cnn) donald trump is trying to orchestrate a pivot in his troubled campaign. he began by shaking up his campaign staff by bringing in stephen bannon, an executive from breitbart news, to take on the top post, effectively demoting paul manafort, who then chose to resign.









in one of the more shocking moments of his campaign, trump admitted to saying the "wrong thing" at some points in his presidential quest and said he regretted doing so.









there is good reason for him to attempt to change the dynamics of this campaign. right now, everything seems to be coming apart. trump is doing horribly in the polls -- in swing states, in red states and in blue states. each remark manages to alienate more voters and stirs greater doubts about his capacity to be president. the new york times reported that he is now even struggling with his core of supporters, white men.









at this point, democrats might be heading toward a landslide victory, capturing the white house by large margins, securing control of the senate for the first time since 2010 and possibly, just possibly, taking over a majority of the house of representatives (though the odds of that remain low). republicans are running scared and there is ample reason for them to feel this way.









pivoting to a "new trump," as some are calling it, won't be easy. it isn't easy for any candidate at this point in the campaign and it certainly won't be easy for donald trump. making a statement and shaking up his campaign team, which he has done before, won't be enough to do the trick.









there is a reason that social scientists have pushed back against "game change" accounts of presidential campaigns. the most difficult challenge that trump currently faces is the overwhelming evidence from aggregate poll numbers which point to big problems for the republican ticket.









while there are always a few polls that emerge to suggest the race might be tightening, a broader look at the data suggests that trump is consistently struggling in almost every part of the country, including in very red states like utah.









my colleague at princeton, sam wang, has shown how when you put all the polls together, trump doesn't really stand much of a chance of winning. right now, clinton is running 5.8 percentage points above president obama's standing versus 2012 gop candidate mitt romney at the same point in the campaign four years ago. although pundits love to remind audiences of famous polling errors such as "dewey beats truman" in 1948, wang reminds us that those moments are quite exceptional.









nervous republicans must also face the fact that trump is the person who he is. although people have speculated for months that trump would pivot to a mode more appealing to the wider audience of general election voters, as opposed to the conservative base of the gop, he has continually failed to stay that course. occasionally he gives carefully calibrated speeches using a teleprompter, but then immediately reverts to his more extreme messages.









trump has shown no interest in backing away from the kind of provocative style that brought him to the dance. his advisers have not been able to push him in a different direction and as he slips in the polls, his instincts seem to be to double down on this kind of behavior.









always the showman, trump has little personal incentive to back away from what has now become his brand of speaking. and an adviser such as bannon is likely to favor the "let trump be trump" approach, rather than try to craft a new candidate at this late stage. in fact, he might push him even further in his provocation, given what breitbart.com has specialized in.









african-americans won't start turning to trump after the kinds of statements he has made over the course of his campaign, including his slow response to calls to dissociate himself from white supremacist supporters.









nor will the gop as a whole easily reverse its disadvantage with african-american voters unless it works to reverse the damage that has been caused by the party's positions on key issues like voting rights, economic inequality and police violence. the fact that trump hired an executive from the polemical breitbart news is not evidence he moving toward a different mentality.









as the summer comes to a close, we are pretty late into the election game. there are some moments in us history, such as hubert humphrey's surge in the fall of 1968, when candidates have been able to rapidly gain ground on their opponents (of course humphrey still lost the election). but by and large those comebacks don't happen too often. given the chaotic and underdeveloped state of trump's campaign field operation in the swing states, it will be extremely difficult for him to achieve anything of this sort.









of course politics can take surprising and unexpected turns, as trump's nomination proves. the three presidential debates, which begin in late september, offer an opportunity to change the direction of the race. and the possibility of some kind of crisis or data dump creates room for campaigns to shift course. most often, however, there is no october surprise.









fundamentally changing the direction of the campaign is going to be extremely hard for the gop. the recent comments and new campaign staff won't be enough. republicans might conclude that they will be better off focusing on the senate and house races than placing too much hope in the idea that the man at the top of the ticket has a big trick up his sleeve.
for trump, turning this around won't be easy
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