Story highlights Bernie Sanders slammed Donald Trump's attempts to put the "birther" issue to rest

Sanders also pressed the case for Clinton and presented the 2016 election as a stark choice

(CNN) Sen. Bernie Sanders sarcastically dismissed a statement from Donald Trump's campaign saying that the Republican nominee now believes President Barack Obama is a US citizen, arguing that the "birther" movement is about "delegitimizing the first African-American president in the history of our country."

Appearing Friday on "New Day" on CNN, Sanders offered a caustic rejection of the Trump campaign's statement, put out by spokesman Jason Miller on Thursday night.

"Well isn't that something. My word! After eight years of having President Obama as president, Donald Trump now thinks he's a legitimate president. Well I'm just overwhelmed with emotion," Sanders told CNN's Chris Cuomo.

"Look, this is pathetic. And this goes to the root of what Trump's campaign is about," said Sanders. "Let's be clear -- it's about bigotry. You remember, let's all remember, that a few years ago, Donald Trump was the leader of the so-called 'birther' movement. And what the birther movement was about was not being critical of Obama. This is democracy, we can criticize Obama. It was delegitimizing the first African-American president."

"It is not acceptable for a candidate for president of the United States to be arguing whether or not our President was born in this country."

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