John F. Kennedy‘s grandson, Jack Schlossberg, is not holding back in his criticisms against Vice President Mike Pence.

In a recent Wall Street Journal op-ed, Pence, 60, called on Senate Democrats to break ranks and oppose the articles of impeachment brought against President Donald Trump.

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In his op-ed, Pence quoted former president Kennedy’s 1957 Pulitzer Prize-winning book, Profiles in Courage, in which Kennedy praised Republican Senator Edmund Ross for breaking ranks and voting to acquit President Andrew Johnson when he was impeached in 1868.

In a series of tweets, Schlossberg, who is the 27-year-old son of Caroline Kennedy and Ed Schlossberg, wrote, “Pence is right to celebrate Ross, a public servant who, foreseeing his own defeated (sic), nonetheless summoned the courage to vote his conscience, and put the national interest above his own. But let’s not be confused.”

Image zoom Paul Marotta/Getty Images; Press Association via AP Images

“@realDonaldTrump was impeached because he did the exact opposite — he put his own interests ahead of our country’s national security and, in the process, broke federal law,” Schlossberg said.

He also claimed that Pence and Congressional Republicans have “failed the test of courage,” adding, “Rather than risk their career or endure personal reprisal, they excuse the President’s and others’ admitted wrongdoing and disgraceful behavior.”

Schlossberg continued: “I would argue instead that today, as in 1865, political courage might require a Republican Senator to risk his or her own political future by breaking lockstep from the President and agree to hear from witnesses, review the evidence, and put the national interest above their own.”

Last Thursday, after lawmakers in the House of Representatives delivered the articles of impeachment against Trump, 73, the Senate officially opened the trial against him, which is expected to effectively begin on Tuesday after the Martin Luther King Jr. holiday weekend.

Trump has officially been accused of abuse of power and obstruction in connection with the Ukraine scandal. A months-long investigation in the House broadly corroborated the case against Trump that he withheld support of Ukraine’s government to pressure leaders there to investigate his political rivals.

Still, Trump has adamantly insisted he did nothing wrong and on Wednesday labeled his impeachment a “hoax.”

Image zoom Donald Trump Evan Vucci/AP/Shutterstock

The impeachment trial will determine whether he is convicted on the charges and removed from office.

“President Trump warrants impeachment and trial, removal from office and disqualification to hold and enjoy any office of honor, trust, or profit under the United States,” Rep. Adam Schiff said last Thursday in reading out the impeachment articles in the Senate, according to The New York Times.

Schiff, a familiar Trump foe who led part of the House investigation into his conduct with Ukraine, is one of seven House managers for the trial. An impeachment manager is analogous to a prosecutor.