Kentucky GOP Sen. Rand Paul said Wednesday the fading American Dream  will not be restored unless the country elects a new president, then directed his sharpest criticism at President Obama’s health care law, saying “the whole damn thing is unconstitutional.”

The first-term senator made his remarks at the Republican national convention, using working-class Americans and immigrant families like his to make his point.

In an open message to Obama, Paul said telling small-business owners that “You didn’t build that” insults "the dishwasher, the cook, the waitress. You insult anyone who has ever dragged themselves out of bed to strive for something better for themselves or their children.”

Paul said such a comment also insults a Cambodian family that owes a donut shop that he and his family like to frequent.

“Their family fled war-torn Cambodia to come to this country,” he said. “Mrs. Taing told us that the family works through the night to make donuts. The Taing children have become valedictorians and National Merit Scholars. The Taings from Cambodia are an American success story, so Mr. President don’t you go telling the Taings: 'You didn’t build that.' "

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Paul also spoke of his great grandfather who came to the United States penniless and his grandfather, who raised children who became doctors, ministers, accountants, professors and “a certain congressman from Texas” who ran for president of the United States.

Paul was referring to his father, Rep. Ron Paul, who was honored with a one-minute video before his son spoke. 

“How are we going to fix this?” Paul asked in endorsing GOP presidential nominee Mitt Romney, “one option: We have to have a new president.”

“I believe that someone is our nominee: Governor Mitt Romney,” he said.