By Gerald F. Seib 

It took but a few minutes into Monday night's presidential debate for the two contenders to distill the essence of the case they are making for taking over the White House. And they did so in no uncertain terms.

Democrat Hillary Clinton portrayed herself as the woman with a plan, who has been around the block in Washington, who is ready to hit the rich and battle "trickle-down economics" -- and who, by the way, wasn't going to be afraid to go after her opponent, who, she said, "has called women pigs, slobs and dogs."

Republican Donald Trump painted himself as the agent of change, whose opponent has spent years failing to fix the nation's problems while he was building a business. He proclaimed himself ready to rip up trade agreements that the "hack" politicians love, and who would stand directly in the path of companies that want to move overseas. His opponent, he said, has both a bad track record and bad judgment: "Hillary has experience, but it's bad experience."

If presidential debates are supposed to illuminate differences and get candidates to engage directly and critically, this one did its job almost from the outset. It was tense and engaging, and, in its closing minutes, turned nasty -- and eliminated any doubts that Mrs. Clinton was willing to get into attack mode with Mr. Trump. Oddly, Mr. Trump missed some opportunities, failing to weigh in on his signature issue of cracking down on immigration and failing to take on Mrs. Clinton for calling some of his supporters "deplorable."

On economic affairs, Mrs. Clinton essentially promised to be the guardian of the middle class, who has plans to raise the minimum wage, ensure women equal wages, build infrastructure and encourage solar energy. Government investments would create jobs, she said simply and directly.

And she made no apologies for her experience. "I prepared to be president," she said. "And I think that's a good thing."

Mr. Trump, in turn, delivered his simple, even blunt formula for reviving the economy: "Our jobs are fleeing the country" because Mexico and China are stealing them, he said. "They are using our country as a piggy bank to rebuild China."

He would fix trade injustices that politicians such as Mrs. Clinton have spent decades either creating or ignoring, he pledged. "You have had 30 years" to fix such problems, he told Mrs. Clinton repeatedly. Meanwhile, he promised that his tax cuts -- big tax cuts -- would do for the economy what Ronald Reagan's tax cuts did for it three decades ago.

There was plenty of snarling along the way as well. She charged that he succeeded in business only after getting a multimillion-dollar head start from his father, and that he subsequently stiffed small-business people as he climbed to the top.

She didn't merely imply but charged directly that Mr. Trump hasn't released his income-tax returns because he has something to hide -- most likely, she said, that he hasn't actually paid much in federal income taxes. And she charged he consciously spread a racist lie that President Barack Obama was born overseas.

He, in turn, pledged that he would release his tax returns when she finds the 30,000 emails deleted from the personal email system she used while secretary of state. And by the way, he said, creating that private email system wasn't a "mistake" as Mrs. Clinton has said, but rather done intentionally to hide what she was doing. Mrs. Clinton, he charged, is afraid to use the words "law and order," while he is more than prepared to do so.

He made no apologies for his argument that allies, including Japan, have to pay more for their own defense, relieving the U.S. of the burden. She said in response that America's allies need to know that "we have mutual defense treaties and we will honor them." He said she lacked the stamina to be a tough negotiator; she said she traveled to 112 countries as secretary of state.

In short, this debate was tough but also enlightening. At times, Mr. Trump seemed a bit too eager to interrupt and play the part of the bully that Democrats charge he is. And in dismissing Mr. Trump's intense arguments with a chuckle and a nod of her head, she occasionally seemed on the verge of appearing smug, which Republicans charge she is.

But it was a struggle in which the two contenders did, in fact, play to their strengths -- he to his ability to connect with voters on visceral terms, she on her ability to move smoothly from subject to subject with an air of authority. They will not shrink from the fight in the two debates that remain.

Did they win over the voters they need? That's much less clear. Because they largely played true to form and expectation, it's possible they didn't change minds so much as confirm existing perceptions.

If nothing else, though, the debate clarified the very real choice, and the contrast in style, substance and background that this election has produced.

Write to Gerald F. Seib at jerry.seib@wsj.com

(END) Dow Jones Newswires

September 27, 2016 00:14 ET (04:14 GMT)