Donald Trump has surged in national polls but his prospects for winning the presidency remain dim.

His weakness among suburban voters, especially women, leaves him trailing by about 7 points in Pennsylvania, and it is tough to construct a plausible scenario giving him the 270 electoral votes needed to win without the Keystone State.

Similarly, his strength with blue collar men likely will not be enough to overcome his weakness among more-educated, middle class women in several other battleground states — even if not by such a wide margin.

New revelations about Hillary Clinton’s emails and her obsession with secrecy, laid bare by her bout with pneumonia, gave Trump an opening to reintroduce himself as a more reasonable choice to those women.

Instead, he resurrected the birther issue and pounded on the evils of immigration and free trade, and poor Mexico.

Middle-class women work outside the home, and often employ or work alongside immigrants.

They shop at Wal-Mart, are skeptical about balancing family budgets without inexpensive goods from China, and many recognize the United States can’t simply rip up NAFTA without wholly destabilizing Mexico and causing millions more to try to cross our southern border.

A more reasoned approach to immigration—one giving priority to applicants with skills in short supply and committed to assimilating — would benefit our economy, but he still talks about building a wall and getting tough to make our country safe.

It reminds me of a mother’s admonition, “If you yell, no matter what you say, people remember you as a screamer and not your message.”

On trade, Trump has failed to effectively state the obvious. We want to trade with Mexico, China and others and benefit from what they do best, but we don’t want the game rigged by foreign government subsidies and other gimmicks so that we can’t make and sell what we do best.

It’s all about giving everyone a chance to prosper — including the most ordinary Americans.

His advisers indicate that is where he would take U.S. trade policy, but when he threatens to rip up NAFTA and slap a big tariff on China — without explaining how he would use those to negotiate more equitable terms and sustain international commerce — he is screaming.

Historically, well-educated suburban women vote Republican, but the culture has changed since George W. Bush was elected. The party has not adequately moved with the women that are an important part of that change.

Consider how much the country has altered views on gay marriage and other gender-related issues, and even the minimum wage. Americans are less hued to religion, and whatever their beliefs are much less inclined to generalize about Catholics, Protestants, Jews and most importantly, Muslims.

Frustrations with health care insurance companies, rising cable rates and chiseling by banks like Wells Fargo have impelled women to look more toward government for solutions.

They may not like Obamacare, for example, but if Trump wants to come across as an attractive alternative to Clinton, he needs to do more than promise to replace Obamacare with something great.

He can’t leave the minimum wage to the states, and he must display some leadership to calm the culture wars on gender, race and religion — instead of inflaming those by promising to subject Muslims to special scrutiny.

His child care proposals were a small step in the right direction, but even those he left to his daughter to champion.

He can’t subcontract to surrogates convincing educated women he is worthy.

The debates will give Trump the national stage and his last real chance to more effectively present his positions on immigration, trade and other issues that strike directly at the interests of middle-class women.

Promises to make America great and safe — without explaining clearly and simply how his specific policies would make ordinary Americans better off and more secure — would ensure that Clinton wins.

Peter Morici is an economist and business professor at the University of Maryland, and a national columnist. He tweets @pmorici1.