According to the Washington Post, no matter what Donald Trump tries to do, he can't undo what he's already done in this campaign. From their article "A Trump reboot? Impossible", they quote the Wall Street Journal when it said:
"The Wall Street Journal editorial page, previously eloquent in its opposition, urges Mr. Trump to behave “in a way that reduces his epic unfavorable numbers with many voters.”
This is what the Post thinks is impossible: Trump changing who he is, how he behaves, what he stands for, and explaining how his rudimentary and simplistic policy ideas could actually be implemented. Since they don't think he can change, the Post certainly doesn't advocate him being elected. And one of the reasons why is what they think would happen if he was:
"His nomination is a calamity for the Republican Party, and Republicans will have to sort out how it happened and how they might recover. But the more urgent task is to ensure that Mr. Trump does not become a calamity visited on the United States and the world. For all his unpredicted success, the number of Americans who have voted for him so far amounts to only 4.7 percent of eligible voters, according to a calculation by the organization FairVote. As conservatives of principle recognize, he can be stopped, and he must be."