Filings with the Federal Election Commission indicate the first-term Kentucky Republican's senatorial re-election fund and his political action committee received $1.9 million from January through June, The (Louisville) Courier Journal reported Sunday.
Rubio has raised $2.75 million; Ryan $2.3 million.
Still, what Paul has collected this year nearly ties the $2.15 million raised in the previous two years combined.
Sen. Ted Cruz of Texas and former Sen. Rick Santorum of Pennsylvania, both rumored to have a similar interest, are well back in the pack. Cruz has raised $1.6 million while Santorum received $138,396.
Paul says he will make a decision about running for president after the 2014 mid-term elections.
Paul has spent slightly more than $1 million since January, FEC records showed. He had nearly $1.4 million on hand at his two committees.