President TrumpDonald John TrumpTrump to oust Nielsen as early as this week: report California wildfire becomes deadliest in state’s history Sinema’s Senate win cheered by LGBTQ groups MORE's supporters chanted “lock her up” ahead of his arrival at a rally in Mosinee, Wis., on Wednesday evening, just hours after the Secret Service said it found "potential explosive devices" in mail sent to former Secretary of State Hillary ClintonHillary Diane Rodham ClintonSinema invokes McCain in Senate acceptance speech Sinema defeats McSally in Arizona Senate race Hillicon Valley: Social media struggles with new forms of misinformation | US, Russia decline to join pledge on fighting cybercrimes | Trump hits Comcast after antitrust complaint | Zuckerberg pressed to testify before global panel MORE at her home in Chappaqua, New York.

Video of the rally showed the crowd chanting the phrase as Sen. Leah Vukmir (R) delivered remarks shortly before Trump’s scheduled appearance.

The chant, which has become a regular feature of Trump's rallies since his presidential campaign, came hours after authorities discovered potential explosive devices had been sent to Clinton’s New York residence, in addition to other Democrats including former President Obama, Rep. Maxine WatersMaxine Moore WatersJudd Gregg: With the midterms over, opportunity knocks April Ryan: Trump relishes verbal attacks against women of color CNN's Kirsten Powers: Trump knocking black reporter for 'stupid question' is 'classic white supremacy' MORE (Calif.) and former Attorney General Eric HolderEric Himpton HolderTrump's shortlist for attorney general takes shape Pipe bomb suspect to be held without bail Pipe bomb suspect to appear in court on Election Day, prosecutors say MORE.

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Each of those targeted by the suspicious packages have been criticized repeatedly by Trump, who condemned the attempted attacks as “abhorrent” during remarks from the White House East Room on Wednesday afternoon.

“We are extremely angry, upset, unhappy about what we witnessed this morning and we will get to the bottom of it,” he said.

White House press secretary Sarah Huckabee Sanders also said the president and administration officials are monitoring the developments.

"Our condemnation of these [despicable] acts certainly includes threats made to CNN as well as current or former public servants. These cowardly acts are unacceptable and wont be tolerated," she tweeted.

Clinton and other bipartisan lawmakers called for officials to dial back their rhetoric in response to the attempted attacks.

Trump was stumping for Wisconsin Gov. Scott Walker (R) in his reelection bid against state schools superintendent Tony Evers (D), and Leah Vukmir, who is challenging Wisconsin Sen. Tammy BaldwinTammy Suzanne BaldwinSinema’s Senate win cheered by LGBTQ groups Midterms: The winners and losers Senate GOP beats expectations with expanded majority MORE (D).

Walker is battling Evers in a tight race, which RealClearPolitics has dubbed a "toss-up." A RealClearPolitics average of polling gives Evers a 3.6 percentage point edge in the race. 

Baldwin has a double-digit lead over Vukmir, according to a recent Marquette Law School survey of likely voters.

--Updated on Oct. 25 at 7:33 a.m.