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Manuel Balce Ceneta, File, Associated Press
FILE - In this Jan. 13, 2015 file photo, Sen. Rand Paul, R-Ky. speaks in Washington. Paul is both a senator and a medical doctor, a combination no other prospective GOP candidate for president can match. But it means added scrutiny on Paul, too, such as when he said this past week amid a measles outbreak that vaccinations and mental disorders are linked in children _ a connection with no scientific basis.

DES MOINES, Iowa — As a doctor, Kentucky Sen. Rand Paul has a rare set of credentials at the intersection of science and politics.

But the glare of the 2016 presidential race is searing, and under it, the Republican lawmaker had a rough week.

On Friday night in Iowa, Paul faced likely voters for the first time since he responded to questions about a measles outbreak by saying he had heard about children who got vaccines and ended up with "profound mental disorders."

That assertion has no basis in medical research, and Paul clearly was still upset about how his comments had been received.

Paul intends to highlight his background as a physician in hopes of gaining an advantage if he gets into the race.