Citing his work in political advocacy pushing for gun control and Obamacare, Kentucky Republican Sen. Rand Paul threatened Wednesday to place a hold on President Obama’s Surgeon General nominee.

In a letter to Senate Majority Leader Harry Reid, Paul explained his objection to Dr. Vivek Murthy, Obama’s choice for the position.

“I have serious concerns about Dr. Murthy’s ability to impartially serve as ‘the Nation’s Doctor’. The majority of Dr. Murthy’s non-clinical experience is in political advocacy,” Paul, himself a medical doctor, wrote Wednesday. “As you know, Dr. Murthy is the co-founder of Doctors for America, born out of the campaign organization Doctors for Obama, and it is a project of the left-leaning think tank Center for American Progress and has worked closely with Organizing for America, President Obama’s political organization.”

According to Paul, Murthy’s “primary policy goals” have been pushing stricter gun control laws and Obamacare, and that Murthy refers to “guns as a public health issue on par with heart disease and has diminished the role of mental health in gun violence.”

“As a physician, I am deeply concerned that he has advocated that doctors use their position of trust to ask patients, including minors, details about gun ownership in the home,” Paul wrote. “His organization has also advocated that physicians collect and report data on gun ownership to the Federal Government and increasing Federal funding for gun control research.”

Paul argued that Murthy’s political activity has disqualified him from “being Surgeon General because of his intent to use that position to launch an attack on Americans’ right to own a firearm under the guise of a public health and safety campaign.”

In placing a hold on the nominee, Paul will object to any unanimous consent agreement or waiver of any rule, meaning the Senate will need to invoke cloture to advance the nominee, which under new rules requires 51 votes.

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