Fox News contributor Bill Bennett said on Tuesday that Senate Minority Leader Chuck Schumer, D-N.Y., wants to add witnesses to the Senate impeachment trial because he senses House Democrats' case for impeachment is “weak.”

“When these articles finally came down: abuse of power and obstruction of Congress. They seem very half-hearted, seem very weak to me. Seem that way to a lot of people. I think he knows that he needs more,” Bennett told “America’s Newsroom.”

SCHUMER SAYS HE WANTS IMPEACHMENT TRIAL FOCUSED ON FACTS, NOT 'CONSPIRACY THEORIES,' AS HE BALKS AT GOP CALLING WITNESSES

Schumer said during a news conference Monday that any Senate impeachment trial should be “focused on the facts that the House presented, not on conspiracy theories” – an apparent slight at Republican attempts to cast aspersions on former Vice President Joe Biden and his son Hunter’s business dealings in Ukraine.

“We ought to stick to the facts, and if there are other witnesses who might have witnessed what happened, who might have very strong evidence on the facts that the House presented. I'd certainly want to hear who they are,” Schumer said.

In a letter to Senate Majority Leader Mitch McConnell Sunday, Schumer specifically asked that four witnesses be called during the trial: Mick Mulvaney, the acting White House chief of staff; Robert Blair,  a senior Mulvaney adviser; John Bolton, the former nation-security adviser; and Michael Duffey of the Office of Management and Budget.

Bennet doubled on his argument by saying that Schumer wants more witnesses because neither of the articles for impeachment defines a violation of the law, “unlike in the Clinton [impeachment] case.”

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“For good reasons or bad, the Clinton impeachment was about things that the public understood and even [took] some degree of prurient interest in ... This ridiculous abuse of power by President [Bill] Clinton and a violation of the law: lying to a grand jury, lying under oath --It’s a different situation here entirely.

“These [House Democrats impeachment] charges seem to me to be quite weak,” Bennett added.

Fox News' Andrew O'Reilly contributed to this report.