One of the primary reasons is that Trump's positions on very, very big issues appear to be fluid, his language and policy commitments a little more than imprecise. More than one observer of the Trump campaign has noted that Trump's sometimes-incendiary statements followed by professed flexibility is a kind of sales tactic unto itself, making it difficult for any one to pin him down with questions, frame a solid counter-argument or point out the flaws in Trump's plans. It allows Trump to occupy a semi-squishy middle or, at the very least, alienate as few voters as possible despite running a campaign built around the willingness and superior ability to offend.
Trump has even taken to describing this process as part of his skill set -- negotiating and cutting deals. Doubt that? Consider a few recent but major examples that Trump is now renegotiating, so to speak.
1. Entitlement program cuts -- not now, not ever
Between October and April, Trump said some version of this -- a lot. AARP even made a list. Trump was willing to do everything in his power to avoid cuts, promising that he would "save" Medicare and Social Security -- two of the nation's biggest entitlement programs which have together significantly reduced senior citizen poverty, without cuts.
Then, in early May, a Trump adviser told reporters that, if elected, Trump would consider changes -- including possible cuts -- to both programs.
2. A four-tier tax plan to help the middle class -- but really, really help the wealthy
In September, Trump revealed a tax plan that he said would shine an ugly light all other tax plans, in part because it would focus on helping the middle class. Tax plans are often complicated with lots of moving parts, but the essence of Trump's plan was a 25 percent across-the-board tax cut for all income tax payers. The Tax Policy Research Center assessed Trump's plan and found that the biggest beneficiaries would, in fact, be the wealthy.
But on a weekend news program this month, Trump suggested that he didn't particularly care for that feature of his plan himself and would want to make changes. Tax rates would have to be set after -- you guessed it -- negotiating with Congress.
"I'm not under the illusion that that's going to pass," he said. "They're going to come to me."
3. Leveraging debt repayment -- and even the national debt -- as a huge way to secure repayment discounts
What can we say? It's been a busy month for Trump. The candidate suggested that he would try to negotiate debt repayment discounts with the nation's creditors. It's a practice he's used in his own businesses.
But the suggestion set off alarms with economists who warned that the most likely route to such discounts would require a President Trump and the United States to threaten that payments would not otherwise be made. A default or threatened default might secure some repayment deals but would also likely do significant harm to the country's credit rating and cause a spike in interest rates.
Not long after that, Trump basically told reporters that the press had misunderstood. He is aware of the possibility of interest-rate increases and overall inflation but he would leverage that to the advantage of the country, use the government's ability to print money to avoid a default and ultimately leave the country more flush. Plus, Trump told reporters, America can trust his expertise in this area. “I’m the king of debt,” he said. “I understand debt probably better than anybody. I know how to deal with debt very well."
4. Ban Muslim immigration
In December, Trump's campaign put out a press release that stated his position plainly: The U.S. government should put a temporary ban on all Muslim immigration and travel to the United States until someone can"figure out what's going on." Trump said pretty much the same to several reporters.
Then, this week, Trump seemed to downgrade the proposal from a policy idea or plan that would be implemented in a Trump administration to a "suggestion" -- something that could also be negotiated, apparently.
5. Wages are too high
Live, on tape, in the midst of a November Republican primary debate from his customary podium slot at center stage, Trump pronounced American wages "already too high" -- one of the things curtailing the country's economic competitiveness. He honestly and truly did.
Trump defended his idea the next day, too. By the end of that week, Trump was denying that he ever said such a thing. More recently, Trump told reporters he would like to see a minimum wage increase but would prefer to see that happen due to the action of different state legislatures.
6. The biggest, baddest, most beautiful border wall the world has ever known
This is the one idea that has become emblematic of the Trump campaign -- a seemingly simple solution to an incredibly complex problem with both economic and human dimensions. Throughout most of the campaign, Trump talked of a border wall as an essential element of his plan to deal with illegal immigration and claimed that he has a method to force Mexico to finance the wall. He would be tough. He would be firm where other president have not.
But in March, Trump told the New York Times that he would be willing to negotiate some of the wall's details. Perhaps, Trump said, the wall could stand a foot or two shorter than previously described.