The unofficial Rand Paul presidential campaign is gaining steam, selling out speech venues through June as he nears a decision to act on his popularity and officially announce a 2016 bid for the White House.

The Tea Party favorite and leader of the "liberty wing" of the Senate GOP is also raising money fast for his Rand PAC leadership political fund and his Rand Paul 2016 PAC, set up to fund his re-election as Kentucky's junior senator.

Top aide Doug Stafford said the senator raised $1.5 million in the first four months of this year. "That's not a bad initial take for it being only 2013," he told Secrets. That works out to $12,500 a day.

"People want to hear what he has to say," added Stafford.

Ever since Paul decided earlier this year to take his message of less government, more freedom coast to coast and build a 50-state platform on which to run, Rand fans have been lapping it up.

Recently in Iowa, for example, the venue for his speech at the GOP Lincoln Day fundraising dinner in Cedar Rapids had to be expanded. There he directly smacked the leading Democratic 2016 presidential candidate, former Secretary of State Hillary Clinton, accusing her of failing to protect the U.S. Consulate in Benghazi. "It was inexcusable, it was a dereliction of duty, and it should preclude her from holding higher office," Paul said in the state that holds the first-in-the-nation presidential caucus.

His next stop is New Hampshire, host of the nation's first presidential primary, and that event is sold out.

After that is a May 31 speech at the Ronald Reagan Presidential Foundation & Library, whose website states: "This event is SOLD OUT."

And his June trip to attend GOP events in South Carolina, the first Southern state to vote in the primaries, is full.

Stafford noted that in each case, the state parties have sought out Paul in part because he is such a big draw. "It's not Rand looking around, saying 'I want to go here,' " said Stafford. "It's the leaders of these parties recognizing that the folks in their party want to hear from Rand."