As the 2016 presidential election heats up, Republican hopefuls are racking up absences in the Senate.

Sens.(Fla.),(S.C.) and(Texas) missed more roll call votes during 2015 than any other senators, according to data released this week from C-SPAN.

Meanwhile, Graham, who suspended his campaign earlier this month, missed 28 percent of roll call votes during 2015, and Cruz missed 24 percent.

While many of the absences were on procedural votes, the three senators also missed votes on nominations or major legislation.

For example, Cruz drew widespread criticism earlier this year over missing the final vote to confirm Loretta Lynch as attorney general; Rubio most recently missed votes on the end-of-the-year government spending bill

Rubio's attempt to run for president while also keeping up his Senate duties has received constant criticism, coming under the media spotlight as early as January when he missed a vote on the Keystone XL pipeline to fundraise in California.

His Senate voting record is also drawing increased scrutiny from his rivals for the Republican presidential nomination.

In a TV ad this week, a super-PAC supporting former Florida Gov. Jeb Bush's White House bid highlighted Rubio's absence from a classified briefing after the November terrorist attacks in Paris.

Paul, who is also running for the presidential nomination, missed 6 percent of Senate roll call votes this year.

The campaigns have repeatedly defended their candidates' voting records, suggesting that the senators focus on votes where they can make an impact.

Vitter, who has announced he won't run for reelection, spent most of the year making a failed bid for governor in Louisiana. Reid was absent from the Senate for weeks earlier this year after suffering an eye injury.

On average, senators missed approximately 50 of the 339 votes, according to GovTrack.

Rubio has the worst attendance record, missing 35 percent, or 120 of the 339 roll votes, during the past year, according to GovTrack.