Still unclear: what role, if any, the cases will play in the elections. Trump praised the apprehension of a suspect in the case and said "we must never allow political violence to take root in America." But earlier he had complained that the media's focus on the case was distracting from Republican efforts in the Nov. 6 elections.
The investigation, along with Trump's decision to send hundreds of troops to the U.S. southern border, was colliding with an active weekend of midterm campaigning. Trump will hold rallies in Charlotte, N.C., on Friday night and southern Illinois on Saturday.
Former President Barack Obama was rallying Democrats in Milwaukee and Detroit on Friday while former Vice President Joe Biden was campaigning on behalf of congressional Democrats in New York and Connecticut. Obama and Biden were targets of the mail bombs.
Vermont Sen. Bernie Sanders will campaign for California Democrats during the weekend, and New Jersey Sen. Cory Booker, another of the targets of the suspicious packages, was making several stops in New Hampshire to boost midterm turnout.
A look at midterm campaign activities Friday:
Former President Barack Obama offered a sharp critique of Republicans and the Trump administration during a Milwaukee rally, warning Democrats the nation "is at a crossroads right now."
The former president said Republicans had vowed to take on corruption in Washington but have "racked up enough indictments to field a football team."
Obama questioned the GOP's focus on Hillary Clinton's use of a private email server during the 2016 campaign.
He said if they believed it was a national security concern, Republicans would be "up in arms right now" over reports that the Chinese have listened into the president's phone calls on his iPhone.
Obama was rallying Democrats on behalf of Wisconsin Sen. Tammy Baldwin and Tony Evers, who is challenging Republican Gov. Scott Walker in the November elections.
A political committee supported by billionaire Michael Bloomberg said it was spending $10 million more on the midterm elections, including a $7 million national ad buy.
Independence USA said its first national ad buy would be combined with $3 million in digital advertising aimed at Democrats' winning control of Congress. The injection of money during the final two weeks brings Bloomberg's total spending during the midterms to $110 million.
The former New York City mayor is considering a 2020 Democratic presidential campaign.
In Florida, more than 2 million voters have already cast their ballots and so far Republicans have an edge in the battleground state.
Statistics released Friday by the state Division of Elections show that nearly 560,000 people have voted early this week. Additionally, nearly 1.48 million people have voted by mail.
Nearly 870,000 GOP voters have cast ballots compared with slightly more than 808,000 Democrats. There are more than 13 million registered voters in the state.
Florida voters are choosing whether their new governor should be Tallahassee Mayor Andrew Gillum, a Democrat, or former Rep. Ron DeSantis, a Republican. Outgoing Gov. Rick Scott is challenging Democratic Sen. Bill Nelson in a race that could determine control of the U.S. Senate.
Spending in Montana's Senate race has hit $60 million, shattering a state record as Democratic Sen. Jon Tester faces Republican challenger Matt Rosendale.
A political group backed by Las Vegas gambling billionaire Sheldon Adelson, the Senate Leadership Fund, spent about $1.5 million on anti-Tester ads over the last week and plans to double that amount in coming days, according to campaign filings and a spokesman for the group.
The spending began the day Trump visited Montana to support Rosendale's campaign and bashed Tester for derailing his nominee for Veterans Affairs secretary, Ronny Jackson.
Spending in the contest has reached $60 million, according to an Associated Press tally. That includes $20 million for Tester, $5 million for Rosendale, and $35 million spent by outside groups ($19 million to Rosendale's benefit, $16 million to Tester's.)
Even when accounting for inflation, it easily shatters the prior Montana election record of $47 million during Tester's 2012 re-election campaign.
Associated Press writer Matthew Brown in Billings, Mont., contributed.