Updated at 11:56 a.m. ET at 7/16
(CNN) – While Sen. Marco Rubio's push for comprehensive immigration reform drew some derision from conservatives – particularly his support for a bill that contained a pathway to citizenship for undocumented immigrants – the Florida Republican's fundraising spiked as the measure was debated in Washington.
In the second quarter of 2013, Rubio brought in $3 million - up 31% from his haul in the first three months of the year, according to a source familiar with his financial reports.
That brings Rubio's cash on hand to nearly $3 million - $1.97 million for his Senate re-election committee, and $980,000 for his Reclaim America PAC. Rubio will next be up for re-election in 2016.
Rubio was a member of the bipartisan Senate Gang of 8 that advanced immigration reform legislation this spring. The bill included a pathway to citizenship for undocumented immigrants that hinged upon bolstering border security.
Many conservatives oppose such a pathway, labeling it "amnesty" for law-breakers. Rubio faced a backlash from some on the right, including conservative radio hosts and tea party groups, for his support of the measure. In an attempt to mitigate some of the anger, Rubio and fellow Republicans sponsored an amendment that would ramp up border security.
The bill was approved by the full Senate in June, including gaining the support of fourteen Republicans. Rubio was credited by many as having the conservative credentials necessary to convince some fellow Republicans to support the measure.
The legislation's progress slowed in the House of Representatives, where Republicans are split in their support for a pathway to citizenship.
CNN's Paul Steinhauser and Kevin Liptak contributed to this report.