Senator Marco Rubio, the Florida Republican, has a 70 percent attendance rate this year, meaning that for the 30 percent of the days he was out, he missed 69 votes.

Senator Ted Cruz of Texas, another Republican, isn’t very far behind, with 55 missed votes, or 77 percent attendance.

Both senators have been on fund-raising binges in the weeks since they announced their presidential campaigns, trying to rake in as much as possible before the June 30 deadline that marked the end of the second quarter.

But their colleague, Senator Rand Paul, Republican of Kentucky, has managed to miss just three votes, giving him a 99 percent attendance record. Mr. Paul must factor in one thing that Mr. Rubio and Mr. Cruz do not: He is asking Kentuckians to re-elect him as senator this year while at the same time running for president.