The libertarian Texas lawmaker, however, said he will continue to seek delegates, Roll Call reported.
"Our campaign will continue to work in the state convention process," Paul told supporters. "We will continue to take leadership positions, win delegates and carry a strong message to the Republican National Convention that liberty is the way of the future."
Roll Call said Paul told supporters he would provide an update on the campaign's delegate strategy.
His son, Sen. Rand Paul, R-Ky., last week said his father is not trying to engineer a nomination coup at the Republican National Convention in Tampa, Fla.
Rand Paul said Mitt Romney, the likely GOP presidential nominee, is a good candidate who will be "head and shoulders above (President Barack) Obama."