Less than two weeks before crucial midterm congressional elections, a new element of fear and uncertainty has been injected into the campaign in the wake of pipe bombs that were sent to several prominent Democrats.
Federal authorities announced Friday morning that a suspect in the bomb investigation was arrested. News media, quoting law enforcement sources, said the man was arrested in Plantation, Fla., which is near Miami. Local television stations broadcast footage of police examining a white van with political stickers covering its windows. The vehicle was covered with a tarp and hauled away on a truck.
The mail bombs sparked a renewed focus on the sharp political rhetoric that has long defined the current divisive atmosphere, with calls from both parties to temper the partisanship ahead of congressional elections.
WATCH: Trump Calls for Unity, Blames Media Amid Bomb Threats
A softer Trump?
While announcing the arrest during a White House event, President Donald Trump called on Americans to show unity.
"We must never allow political violence to take root in America," Trump said.
On the campaign trail in Wisconsin late Wednesday, President Donald Trump made a similar appeal for calm.
“We want all sides to come together in peace and harmony. We can do it. We can do it. We can do it. It will happen,” he said.
But Trump later blasted the news media in a tweet.
During his remarks in Wisconsin, Trump also made a plea to moderate the heated political rhetoric on both sides.
“Those engaged in the political arena must stop treating political opponents as being morally defective. We have to do that.”
Democrats pounced on that, countering that Trump has been a key instigator of political tension with his partisan attacks.
Senate Democratic leader Sen. Chuck Schumer and House Democratic leader Rep. Nancy Pelosi issued a joint statement criticizing the president for condoning violence and dividing Americans.
New York City Mayor Bill de Blasio said any effort to temper rhetoric should start at the top.
“This is a very painful time in our nation. It is a time when people are feeling a lot of hatred in the air, and incidents like this exacerbate that pain and exacerbate that fear,” de Blasio said.
Trump has aggressively gone after Democrats in the midterm campaign, including at a recent rally in Montana.
“The Democrat Party has become too extreme to be trusted with power. Their radical policies are a danger to your family and to your country,” Trump said to cheers from the crowd in Missoula.
Trump also emphasized issues that he believes will appeal to his base.
“This will be an election of (Supreme Court Justice Brett) Kavanaugh, the caravan, law and order, and common sense. That is what it is going to be. It is going to be an election of those things,” he said.
WATCH: Bomb Scares Inject Fear and Uncertainty into Midterms
Republicans believe their voters have become energized in the wake of the bitter confirmation battle over Kavanaugh.
And in recent days the president has stoked immigration fears by highlighting the caravan of Central American migrants moving through Mexico.
Immigration remains a core motivator for Trump’s base, former Trump campaign manager Corey Lewandowski said.
“We can’t be a country without borders. No country in the world allows anybody they want to come in without recourse, and we should not be any different than that,” Lewandowski said.
For their part, Democrats are countering with a furious get-out-the-vote effort in the final days of the campaign with help from former President Barack Obama.
“The stakes are high. The consequences of anybody here not turning out and doing everything you can to get your friends, neighbors and family to turn out,” Obama told Democrats at a recent rally in Nevada. “The consequences of you staying home would be profoundly dangerous to this country, to our democracy.”
Former Vice President Joe Biden has also been active on the campaign trail.
“Folks, we know who Donald Trump is. We know. But here’s the deal, guys. The public has to know who we are as Democrats.”
Biden campaigned in Indiana on behalf of Democratic Sen. Joe Donnelly.
Get the voters to the polls
American University political science expert David Barker told VOA that both parties are now focused on mobilizing their voters.
“What both sides need, though, is for their people to turn out on Election Day. And traditionally, that is more critical for Democrats, because Republicans are just more inclined to do it no matter what.”
Democrats remain confident of gains Nov. 6, said Jim Kessler of Third Way, a center-left policy group.
“There is a blue wave coming. The question is, how big? I believe that Democrats will take back the House. I don’t think they will take back the Senate at this point,” Kessler said.
Recent polls suggest Republicans may be rallying to keep some of the Senate seats in states Trump won easily in 2016.
“And some of what has happened in recent days with the Kavanaugh hearing and Republicans kind of coming home as a party are helping in that area,” said John Fortier of the Bipartisan Policy Center. “So, it will be mostly a win for Democrats, with probably a bright spot in the Senate for Republicans.”
It remains to be seen how the late focus on security and immigration will impact the final days of the midterm campaign, a classic October surprise that could determine which party controls Congress for the next two years.