ELIZABETHTOWN, Pa. — Donald Trump is blowing his chance to remake the political map, having squandered leads in this key swing state and slumped in the other Rust Belt states he promised he would swing Republican.
Nowhere is that more obvious than in Pennsylvania, which the billionaire businessman vowed to put into play this year but where voters are recoiling from the man and his mouth.
“I was all for Trump at first, but the things he says, the look on his face — I can’t trust him to have his finger on the [nuclear] button,” said Sam Hess, 74, a registered Republican who, despite strongly agreeing with Mr. Trump on immigration and guns, decided he couldn’t vote for him.
“He doesn’t think. He just says something off the top of his head,” said Mr. Hess. “That’s why he doesn’t get very good press right now.”
Voters across the country are apparently saying the same thing.
After a convention bump that showed him leading Democratic opponent Hillary Clinton in many polls, Mr. Trump has cratered, trailing by 5.8 percentage points in the Real Clear Politics national average of surveys.
Worse yet, Mr. Trump has surrendered leads in state polling in Florida, where a Suffolk University survey Thursday put him 6 points behind and showed him falling further behind in New Hampshire, where a WBUR/MassInc survey gave Mrs. Clinton a 17-point lead.
In Michigan, he is down 9 points, according to a Detroit News poll. And in Pennsylvania, a Franklin & Marshall survey showed him trailing Mrs. Clinton by a staggering 11 percentage points.
It’s no coincidence that the slide coincides with Mr. Trump’s feud with the Muslim parents of an Army captain who died serving in Iraq. Polling shows the vast majority of voters saw Mr. Trump’s criticism of the family as unacceptable.
Mr. Trump compounded his problems with some voters this week after he accepted a veteran’s Purple Heart decoration. The businessman said he “always wanted to get the Purple Heart,” and added, “This was much easier.”
“One of the first things we’re taught in basic training is you don’t want a Purple Heart — you earn it,” said Ed Loeb, an Air Force veteran who runs a small business in Elizabethtown.
This is an area Mr. Trump needs to win overwhelmingly. The surrounding Lancaster County went for 2012 Republican nominee Mitt Romney, 59 percent to 40 percent, even as the state overall gave President Obama 52 percent of its vote.
But Mr. Loeb, who voted for Libertarian candidate Gary Johnson in 2012, said he is trying to decide between Mrs. Clinton and Green Party candidate Jill Stein.
But whoever gets his vote, it won’t be Mr. Trump, said Mr. Loeb. He said he didn’t trust Mrs. Clinton but at least she was “battle-ready.”
Mr. Trump’s unusual candidacy threatened to upend the political map that has prevailed for the past four elections. Republicans won in the South and the Plains states, split the Mountain West and Midwest, and lost the West Coast and Northeast.
The Republican presidential nominee appeared poised to make a bid for some of those other Midwest and mid-Atlantic states, with Pennsylvania the biggest and most enticing prize.
“I’m not voting for Hillary; I’m voting against Trump,” said a store owner in Elizabethtown who didn’t want to be identified for fear that his comments would offend customers in the largely Republican town.
“I’m denying him that one vote and hoping to hell it doesn’t come back to haunt me,” he said. “I wasn’t for Hillary and I’m still not, but I guess the devil you know is better than the devil you don’t.”
The store owner, a combat veteran, said the Purple Heart remark reinforced his dissatisfaction with Mr. Trump, whom he called “a schoolyard bully.”
But Barry Cover, who owns a small air conditioning business, said he was sticking with Mr. Trump and didn’t believe polls showing the Republican nominee tumbling here.
“I’m not worried yet,” said Mr. Cover, 52, a retired Marine who served in Afghanistan. “I sure don’t want Hillary in. Right now, I’m so anti-establishment.”