Sen. Bernie Sanders joked Monday that he has a plan to highlight President Trump's difficulty telling the truth if he faces the president on the debate stage in 2020.

"Well, we'll bring a lie detector along," Sanders said on CNN to laughs from a studio audience. "And every time he lies, it goes beep. That would be the first thing."

Sanders, who last week launched another bid for the Democratic Party's presidential nomination, said his criticism of Trump wasn't based on their differing political ideologies. Instead, the independent senator from Vermont said his opposition to the president was predicated on his character as a "fraud" and "pathological liar."

"So we are going to hold him accountable for what he said and for what he did," the self-described democratic socialist said on Monday. "He said he was going to provide healthcare to everybody. And then he proposes to throw 32 million people off their healthcare that they have."

"He said, you all remember, he said, 'I'm a different type of Republican. I'm not going to cut Social Security, Medicare, and Medicaid,' and he brings forward a budget that does just that," Sanders said of Trump. "So I think holding him accountable would be a good start in that debate."

[Related: DNC slaps Trump: 8,000 'lies, his SOTU is no different']