"See how nice I'm behaving?" U.S. President Donald Trump remarked on Wednesday, drawing laughs from supporters in Wisconsin.

The riff, uttered during a political rally with less than two weeks to go before crucial midterm elections, referenced his efforts to adopt a more subdued tone following disturbing news. Hours earlier, a slew of pipe bombs were sent to the addresses of prominent Democrats and activists Trump has assailed in speeches. None exploded; some were intercepted by the Secret Service.

Republican strategists say Trump responded to the bombings in a professional manner. They largely blame Democrats and the media for the hyperpartisan political climate. They don't expect Trump's response to the bombings to figure prominently into how voters cast ballots in midterm elections.

But the president's apparent levity in dealing with one of the largest plots in modern U.S. history to potentially harm prominent officials won't go unnoticed in key states ahead of the midterms, said veteran Democratic strategist Hank Sheinkopf.

This is particularly true in Florida, New York and California, where high-profile terrorist attacks and massacres are still embedded in voters' minds, he added. At least 10 mail bombs were delivered to addresses in these states linked to: Debbie Wasserman Schultz, former chair of the Democratic National Committee, actor Robert De Niro, the CNN headquarters and California member of Congress Maxine Waters.

"Nobody wants to see anybody get blown up. Especially after 9/11 in New York," Sheinkopf said, recalling the Sept. 11, 2001, attacks.

"New York, Florida, L.A., you're talking about places that have experienced an extraordinary level of violence. This provides more impetus for suburban women who are significantly alienated from the president to feel more motivated to vote."

Sheinkopf said the president needs to be less aggressive and act more conciliatory. "It's the smart political thing to do," he said. "A tragedy is nonpartisan."

Political violence will 'motivate voters'

At least two Republican-held districts in New York are in play for Democrats, who have a strong chance of flipping the House.

In California, where the 2015 San Bernardino shootings left14 dead and 22 wounded, there are at least six tight House races that could be won by Democrats.

A higher turnout for Democrats will be key to success.

Watch as Trump talks about unsuccessful bombings:

"Do you see how nice I'm behaving tonight?" Trump says 0:40

"We've seen incredible acts of violence here in Southern California, in San Bernardino, and really around the country. The political violence we've seen, and these pipe bombs, underlines how far we've come from established political norms," said Jason Levin, a Democratic strategist with Cerrell Associates in Los Angeles.

"When you're thinking about Democratic turnout in the midterms, political violence will seek to motivate voters who are deeply uncomfortable with the departure we've seen with those norms."

Trump blames the media

Trump, who praised a Montana congressman who body slammed a reporter as "my kind of guy," referred to the media as the "enemy of the people" and repeatedly described Democrats as an angry "mob," denies his heated rhetoric bears any responsibility for the pipe bombs.

In recent days, he deflected blame to the media. In a tweet, he said media are responsible for "a very big part of the anger we see today in our society."

The pipe bomb deliveries this week targeted some of Trump's most vocal Democratic critics, including the Obamas and the Clintons.

The U.S. president credited himself for restraint on Wednesday night. "Have you ever seen this? We're all behaving very well!" Trump said at one point.

Michael Cornfield, a George Washington University associate professor who studies presidential rhetoric, said it was a familiar performance.

Officers watch over the scene outside the Time Warner Center on Wednesday in New York. U.S. law enforcement officials say a suspicious package that prompted an evacuation of CNN's offices contained a pipe bomb. (Kevin Hagen/Associated Press)

"He does this kind of stuff when he reads from a teleprompter or reads from a piece of paper, and does it in an in-joke voice. Like, 'They're making me do this. You people in the audience know I'd rather not, but they're making me do this.'"

Neither Democratic nor Republican analysts expect him to hold off on attacking opponents for long.

But how the president responds to the threat of mass violence could be a sensitive issue in Florida, where about five congressional seats are in contention. Democratic nominee Andrew Gillum is leading the Florida governor's race by 4.5 points.

Last February, a gunman opened fire at Florida's Stoneman Douglas High School, killing 17 students and staff and injuring 17 others.

William Miller, a Democratic strategist in Miami, urged both parties to dial down the heated rhetoric and warned those who make divisive statements could pay a price at the ballot box.

Trump's willingness to blame the media for polarizing rhetoric might excite his base, Miller said. But "it could also encourage Democratic turnout for those who would say, 'Enough of this.'"

However, blaming the media for polarization does hold appeal for many in his base. A survey from Georgetown University and New York University that was released the same day as news of the pipe bombs found that Republicans rated the media as their least-trusted U.S. institution out of 20 options.

Republican motivations

Many Alabamans agree with Trump that TV news is stoking tribal resentments, said Jon Gray, a Republican strategist in Alabama.

"I do think the president has something there when he talks about the media … You go to CNN, they say Donald Trump's a piece of s--t. When you tune in to Fox News, it's Nancy Pelosi is a piece of crap," he said.

"But is Donald Trump partially responsible for it? Yes, partially."

Former U.S. president Barack Obama was one of the Democrats unsuccessfully targeted by the bomb plot. (The Associated Press)

Gray believes the president genuinely wants the political violence to end, but he doesn't expect Trump's supporters will heed his call. Nor does he think Trump can ever unite the country, which he argues became deeply polarized starting in 2008 with the election of Barack Obama.

"Donald Trump got elected because this country was divided," he said.

"I think he'll be back on the attack by Sunday, if not earlier."

At a recent political event for Republican candidates in Ohio, Republican strategist Ryan Stubenrauch said he didn't hear much reaction about Trump's Wisconsin rally on Wednesday. He said conservatives have expressed horror over the pipe bombs.

"What I'm hearing is, 'Can you believe these crazy people? They're going to get caught and I hope they get what they deserve.'"

For the most part, he said, Republicans are still angry and were motivated to turn out for the midterms due to the treatment of Supreme Court Associate Justice Brett Kavanaugh, whose confirmation was held up by Democrats amid sexual misconduct allegations.

"The Kavanaugh hearings certainly motivated Republicans in Ohio to say, I have to vote," he said. "I don't think a crazed lunatic sending pipe bombs to some politicians and some Democrats is going to motivate anybody."