Democratic frontrunner Hillary Clinton and her allies have begun preparing a playbook to defeat Donald Trump in a general-election match-up that will attempt to do what his Republican opponents couldn't: show that his business dealings and impolitic statements make him unfit to be commander in chief.
Both the Clinton campaign and outside supporters are confident that she and Trump will almost certainly face each other in the United States' general election in November and that the focus is shifting past her hard-fought primary campaign against Vermont Senator Bernie Sanders.
They are now focused intently on researching the billionaire real estate mogul's business record, dissecting his economic policies and compiling a long history of controversial pronouncements that have captivated and repelled the nation in this tumultuous election season.
Neither the Clinton campaign nor several independent super PACs working on her behalf plan to respond with the same brass-knuckles style that Trump has taken with his Republican opponents, aides and outside supporters said.
But in their view, Trump isn't Teflon: Republicans waited too long to go after him, and they went about it the wrong way.
"What the Republicans did was too little, too late," said David Brock, who runs two pro-Clinton super PACs engaged in researching and responding to Trump. "It was petty insults. It was not strategic."
Justin Barasky, spokesman for the large pro-Clinton super PAC Priorities USA, said Republican candidates committed "malpractice" by failing to raise liabilities from Trump's past or aggressively challenge him on offensive or incorrect statements.
Implicit in the effort is real worry about Trump's outsider appeal in a year dominated by working-class anger and economic anxiety. The prospect that Trump could compete for some of the blue-collar voters who have flocked to Sanders, for instance, or to reorder the map of competitive states to include trade-affected Michigan or Pennsylvania, has prompted Clinton's allies to leave nothing to chance.
Yet they also believe that, although Trump has motivated a loyal plurality of supporters in primary contests, he has limited ability to expand that support once the Republican field clears. Because of the litany of controversial pronouncements he has made, they expect a Trump nomination to make it easier to rally women, Latino and African-American voters to turn out for Clinton. In fact, her aides are planning for a historic gender gap between Clinton and Trump.
Given Trump's own willingness to attack his opponents - and his pivot to going after Clinton in recent days - one clear presumption has emerged about the fall contest: It will be ugly.
That's one reason the former Secretary of State plans to counter Trump with high-road substance, policy and issues, according to one senior campaign aide. The idea is to showcase what Clinton's backers see as her readiness for the job without lowering her to what they describe as Trump's gutter.
A central lesson of Trump's primary battle, the campaign aide said, is that he cannot be ignored - but also that he cannot be beaten at his own game. The key will be to maintain stature by focusing on her message of political unity and economic growth and by showing knowledge and strength on foreign issues.
"It's kind of mutually assured destruction: Both sides line up their nukes. It's going to be just ugly and nasty and icky," said another Democrat with longtime ties to the Clinton family. "The winner will not be the least bad of the two. The winner will be the one in the contest of that mutually assured destruction who also has a vision and a message about the future that is both inspiring and credible for the rest of the country."
Brock said: "We will not make the same mistake the Republicans made" by letting attacks go unchallenged.
Said Barasky: "You can't beat him by being him."
- Washington Post, Bloomberg