WASHINGTON, Sept. 9 (Xinhua) -- U.S. Vice President Mike Pence on Sunday criticized former President Barack Obama for returning to the campaign trail and "become so political."

"It was very disappointing to see President Obama break with the tradition of former presidents, and become so political and roll out the same tired argument that he and liberals have made over the last eight years," Pence said in an interview on "Fox News Sunday."

"The truth is, the American people in 2016 rejected the policy and direction of Barack Obama when they elected President Donald Trump," he said.

In a speech Friday at the University of Illinois, Obama offered his most pointed criticism yet of Trump, accusing him of cozying up to Russia, emboldening white supremacists and polarizing the nation.

"You happen to be coming of age" amid backlash to progress, Obama told the students. "It did not start with Donald Trump, he is a symptom, not the cause. He is just capitalizing on resentment that politicians have been fanning for years," he said.

The next day at a campaign for democratic congressional candidates, the former president said the midterm election in November will give Americans the chance to "restore some sanity in our politics."

Trump struck back hours after Obama's Friday speech. "I'm sorry, I watched it, but I fell asleep," the president said. "I found he's very good, very good for sleeping."