President TrumpDonald John TrumpVeterans groups demand end to shutdown: 'Get your act together' Brown launches tour in four early nominating states amid 2020 consideration Pence on border wall: Trump won't be ‘deterred’ by Dem ‘obstruction’ 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 ClintonGillibrand announces exploratory committee to run for president on Colbert Former PepsiCo CEO being considered for World Bank chief post: report Live coverage: Trump AG pick grilled on Mueller probe at confirmation hearing 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 WatersMaxine Waters meets with CBS News representatives over lack of black 2020 reporters Ocasio-Cortez to join House panel overseeing financial sector On The Money: Shutdown Day 25 | Dems reject White House invite for talks | Leaders nix recess with no deal | McConnell blocks second House Dem funding bill | IRS workers called back for tax-filing season | Senate bucks Trump on Russia sanctions MORE (Calif.) and former Attorney General Eric HolderEric Himpton HolderProtecting voices of all voters is critical to free and fair elections Castro to headline forum in New Hampshire after announcing 2020 decision New Jersey governor calls for redistricting reform 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 Baldwin116th Congress breaks records for women, minority lawmakers Kyrsten Sinema swears in to Congress using copy of Constitution instead of religious book Dems say Trump is defying court order by pushing abstinence programs 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.