Anyone who went to both conventions, racing from the shores of Lake Erie to the banks of the Delaware with only a couple of days in between, may be suffering from ideological and tonal whiplash.

Trump addresses the Republican National Convention on July 21. (Michael Robinson-Chavez/The Washington Post)

The Republicans convened last week in a country under siege, imperiled by terrorists, illegal immigrants, criminals and, most ominously, Hillary Clinton. Donald Trump in Cleveland said he would be the law-and-order president and then said it again, and then said it a third time on the off chance anyone missed the concept.

Sen. Cory Booker (D-N.J.) speaks in Philadelphia on July 25. (Jabin Botsford/The Washington Post)

The Democrats have gathered here this week in a still-great, still-hopeful country — but one in desperate need of more love, empathy, justice and equality. That softer tone has emphasized diversity, togetherness and caring. Sen. Cory Booker (D-N.J.), a keynote speaker, used the word “love” 10 times Monday night. Booker said, “We are called to be a nation of love.”

Wednesday’s rhetoric was set to toughen up as the party turned to national security, and the speakers, including President Obama, police officers and former CIA director and Pentagon chief Leon E. Panetta, were to cast Clinton as a cool head and a fighter who is fully qualified to be commander in chief. But for the first two days, the Democrats assiduously positioned themselves as the nurturing party.

Between the convention cities of Cleveland and Philadelphia is an America distressed by job losses but also running on hope fueled by new immigrants. (Lee Powell/The Washington Post)

The contrasting tones carry political risks for each party in what has been a violent and chaotic summer, with terrorist attacks at home and abroad. The Republicans are the party of change this time, led by an insurgent outsider who has never held elected office and says America is in a “moment of crisis.” The Democratic establishment, fully in command here if not always in control, is banking that the public is not eager for a Trump-scale disruption of American political life.

The strategists want to send a message to the public: We hear you. We know how you feel. Beyond the presidential race, there is a battle for both chambers of Congress and numerous state and local contests; these conventions are golden opportunities for the parties to make an emotional connection with voters.

Michelle Obama used the words “kids” or “children” or referenced her daughters or the role of parents 39 times in her much-lauded prime-time speech Monday.

Lauren Manning, a survivor of 9/11, speaks at Wells Fargo Center on July 26. (Saul Loeb/Agence France-Presse via Getty Images)

One of the most effective speeches came Tuesday night, when Lauren Manning, who suffered burns over 82 percent of her body during the 9/11 terrorist attack in New York, spoke of being visited in her hospital room by Clinton, then a senator: “She took my bandaged hand into her own.”

“Certainly fear is a strong motivator, but I think hope and love is a better plan,” said Wisconsin Democratic delegate Karla Stoebig, 33, an aspiring veterinarian who stood in her delegation on the convention floor.

“Our platform is inclusive to all kinds of people, without the divisive, hate-filled rhetoric we saw at the Republican convention,” said Crystal Miller, 35, a beauty adviser in Wisconsin — and, like Stoebig, wearing a “cheesehead” hat.

Walking past Philadelphia City Hall earlier in the day, Carl Levin, the retired six-term Democratic senator from Michigan, and his brother Sander M., a 17-term congressman also of Michigan, paused on the sidewalk to ponder the difference in tone between the conventions.

“His speech was the worst speech in terms of tone,” Carl Levin said of Trump. “It’s obviously an ego speech, and I think that’s not going to work for him.”

“There is an autocratic streak in Donald Trump,” his brother said.

“And that has never appealed to Americans,” Carl Levin said.

“Instead of love, it’s narcissism,” Sander Levin said.

Fear vs. hope may be a simplistic and coarse framing of the presidential contest, but the candidates and their strategists have made that unavoidable. Some traditional issues, such as free trade, are topsy-turvy this year, with Trump taking a position to the left of Clinton. There has been little talk of taxes. Even fractious social issues such as same-sex marriage and abortion have not gotten much attention. Instead there is a sharp contrast in tone.

The skyline of downtown Cleveland is reflected on the windows of the convention center. (Eva Hambach/Agence France-Presse via Getty Images)

Some of the differences between the two conventions have been structural and geographical. The Republicans met in an arena downtown. The smaller dimensions of Cleveland, the natural perimeters created by the Cuyahoga River and Lake Erie, and the decision by locals to take the whole week off meant that downtown Cleveland became a kind of GOP bathtub, all partisans, journalists and law enforcement officers with hardly a regular 9-to-5 worker in sight.

Bernie Sanders supporters a rally at City Hall in Philadelphia on July 25. (Jabin Botsford/The Washington Post)

The Democrats, however, have soaked into the fiber of the much larger city of Philadelphia in a more subtle fashion. The big hotels are full of delegates, and the plazas around City Hall sprout protests reliably on the hour, but the convention proper is a long, hot ride by subway, taxi or Uber down Broad Street, in an arena surrounded by parking lots and media tents.

Another obvious difference is that all the Democrats showed up here, showing off the party’s diversity and attendant divisions. Many of the most distinguished Republicans, including the two most recent Republican presidents, skipped Cleveland, unwilling to associate themselves with Trump. The result was a convention comparatively heavy on testimonials from Trump’s wife and children.

One common feature of both conventions: organizational missteps and unscheduled dissent. The Republicans had a plagiarism kerfuffle and then a stiff middle finger from Ted Cruz in prime time. The Democrats have had their hacked email scandal, the deposing of the party chairwoman and then a steady series of disruptions and a walkout Tuesday evening from Bernie Sanders supporters.

The Sanders partisans marched into one of the media tents, taping their mouths shut to signal their sense of being silenced. Others chanted “The whole world is watching!” in homage to the chant among protesters at the riotous 1968 Democratic convention in Chicago.

Bernie Sanders supporters occupy media tents at the Democratic National Convention in Philadelphia. (Jabin Botsford/The Washington Post)

One of the “Bernie or Bust” protesters, Werner Lange, a 69-year-old retired teacher and a Sanders delegate from Ohio, said he doubted Sanders had endorsed Clinton of his own volition: “They must have gotten to him. My impression is that they threatened his family.”

A hot debate soon broke out in a concourse within the arena, with the Rev. Antonio Anderson of Hope Church Philly telling Sanders partisans that they need to work to get Clinton elected. The Sanders folks vehemently disagreed, saying that she is no better than Trump and is uninspiring.

“Where are the Hillary marches?” one young woman asked.

“Hillary don’t need to march,” Anderson replied, and he pointed to the interior of the arena where the pro-Clinton speeches were ongoing. “They’re in there!”

Party conventions are extraconstitutional; there is nothing in the historic document written in this city in the summer of 1787 that countenances such a thing as a Democrat or a Republican, much less a nominating convention with 15,000 credentialed members of the media and associated protests and policing. So every convention is a staged event, more or less scripted, with improvisations and big moments that no one saw coming.

David Axelrod, a Democratic strategist who now is a talking head for CNN, cautioned against premature story lines coming out of the second half of July.

“Conventions are like four-act plays,” Axelrod said late Tuesday, “and you can only measure them when the play is done.”

“In Cleveland, we heard a message of ‘Be Afraid, Be Very Afraid,’ ” said Sen. Mark R. Warner (D-Va.) as he navigated a crowded concourse at Wells Fargo Center in Philadelphia. He said the more positive message from Democrats was not something carefully orchestrated by party leaders: “We’re Democrats; we’d never be that organized.”

Democrats said in interviews that they think their sunnier message will resonate with voters in November. But this is shaping up as another highly competitive White House contest. One Democratic operative who has worked on a number of campaigns and did not want to be identified because of the sensitivity of the issue, was somber as he rode the subway to the arena.

“I believe love is stronger than hate, but fear wins elections,” he said.