Sen. Rand Paul is set to make official a presidential bid that has long been expected, a senior adviser to the Kentucky Republican said Tuesday, pointing to April 7 as the kickoff date.

Paul's political team has invited backers to a midday event in Louisville. The tea party hero was then set to visit the early nominating states of Iowa, New Hampshire, South Carolina, and Nevada.

The adviser, who demanded anonymity to speak ahead of Paul's public announcement, said the senator, who would also be running for reelection next year, could still pull the plug on a campaign, although that is not expected.

A spokesman for Paul, Sergio Gor, declined to comment.

Paul, 52, would be among the first of the potential 2016 contenders to officially enter the race for the GOP nomination. Details of the kickoff event were first reported by the Lexington Herald-Leader. - AP