(CNN) Democratic presidential candidate Beto O'Rourke repeated his call for Congress to begin impeachment proceedings against President Donald Trump in a CNN town hall Tuesday night in Iowa.

The former congressman from Texas said impeachment is "not something that I take lightly."

"It is an incredibly serious, sober decision to make as a country," he said.

O'Rourke has previously called for Trump's impeachment. He said Tuesday that Democrats should not worry -- as House Speaker Nancy Pelosi has said -- that doing so could energize Trump's base ahead of the 2020 election.

He cited Attorney General William Barr's decision to skip a House hearing and the White House's refusal to comply with congressional subpoenas.

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