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Secretary of State Mike Pompeo sparked an outcry among Democrats over his appearance during the second night of the Republican National Convention, but the participation of a sitting Cabinet member in such a political event is nothing new.

While Pompeo is the first sitting Secretary of State to speak at a party convention, National Review senior political correspondent Jim Geraghty pointed out Wednesday that no fewer than six members of President Obama's Cabinet spoke at the 2012 Democratic National Convention.

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Then-Health and Human Services Secretary Kathleen Sebelius, Secretary of the Interior Ken Salazar, Secretary of Agriculture Tom Vilsack, and Secretary of Education Arne Duncan all took the stage in Charlotte, North Carolina on the "same day" while Veterans Affairs Secretary Eric Shinseki and Karen Mills of the U.S. Small Business Administration spoke the day after.

"If you want to say cabinet secretaries shouldn’t speak at conventions, go ahead. You could try to change the law, but I think it would probably get struck down on First Amendment grounds. You can’t tell someone they can’t speak at all about politics because they have a gov job," Geraghty tweeted. "But Donald Trump and Mike Pompeo didn’t invent this; last night Pompeo just did it with a more dramatic backdrop than past cabinet secretaries."

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During the Obama years, the Office of Special Counsel (OSC) determined that Sebelius violated the Hatch Act, which forbids employees from the executive branch to participate in certain political activities, for saying that it was "imperative” to reelect President Obama at a separate event. The OSC issued a similar finding against then-HUD Secretary Julián Castro, for praising Hillary Clinton during a 2016 interview.

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Under President Trump, the OSC determined last year that White House counselor Kellyanne Conway was a "repeat offender” of the Hatch Act and recommended her removal from the position.

Conway announced this week that she was leaving the Trump administration at the end of the month, though the move was unrelated to her Hatch Act violations.

House Democrats are already launching an investigation into Pompeo over whether he violated the Hatch Act by making his taped address from Jerusalem while touting President Trump's foreign policy accomplishments. HUD Secretary Ben Carson is also set to speak at the convention on Thursday.