Sen. Scott Brown (R-Mass.) is facing allegations that the statements in his new radio ad are 'misleading and untrue' from former congressman Patrick Kennedy, son Ted Kennedy.

In his ad -- as well as in an online video message, op-ed and interviews -- Brown has claimed that the late senator would have disagreed with President Obama's decision to require religiously affiliated organizations to cover birth control in their health care plans. The Obama administration revised the rule to allow faith-based employers to shift the cost of contraceptive coverage to insurers if the employer morally objects to the rule.

Brown's proof is a letter that Ted Kennedy asked Obama to hand-deliver to Pope Benedict XVI in Rome in 2009. In it, Kennedy said he believes "in a conscience protection for Catholics in the health field."

"Like Ted Kennedy before me, I support a conscience exemption in health care for Catholics and other people of faith," Brown says in the new ad.

On Sunday, Patrick Kennedy wrote a letter to Brown and asked him to stop invoking his late father. He said that Brown's characterization of Ted Kennedy's positions was "misleading and untrue."

"You are entitled to your own opinions, of course, but I ask that, moving forward, you do not confuse my father's positions with your own," Patrick Kennedy wrote. "I appreciate the past respect you have expressed for his legacy, but misstating his positions is no way to honor his life's work."

Brown's campaign said it will not stop running the ad.

"When your father told the Pope in his 2009 letter that he supported a conscience exemption for Catholics in health care, he did not mean to put himself on the opposite side of the church or to suggest that he would force them to accept a situation with which they could not abide," Brown replied in an open letter.

“And yet, that is exactly the situation we are faced with today -- despite a failed attempt at compromise, the church remains opposed to the federal government’s intrusion into the affairs of private conscience. I'd like to think your dad would have been working with me to find an accommodation that all sides found satisfactory."

Brown and his challenger, Democrat Elizabeth Warren, have taken starkly different positions on the contraception issue, with Warren recently writing a Boston Globe op-ed that hits Brown for supporting an amendment sponsored by Sen. Roy Blunt (R-Mo.) that would allow employers to deny health coverage for any service that violates their beliefs.