A Senate national security group led by Florida Sen. Marco Rubio since 2013 has hardly held meetings, even though Rubio's office has accepted $100,000 a year for staffing, USA Today reports. Rubio, who is seeking the Republican presidential nomination, has faced criticism that he doesn't show up for votes, though he counters he has been busy in his presidential run.A week before being named co-chairman of the committee, Rubio was part of a group of 11 Republicans and 42 Democrats that voted against a proposal by Kentucky Sen. Rand Paul to defund the Senate arms control task force.Rubio spokesman Alex Burgos told USA Today that the group has done work."Since Marco assumed his role in this group, its leaders have met both formally and informally on national security issues, with most of the work occurring on a staff level," Burgos said. "Marco has engaged on a variety of topics central to the work of this group, including U.S.-Russia arms control, the nuclear deal with Iran and North Korea. His work on these vital national security topics has been aided by the resources provided by this group as well as the information he has obtained from the group's discussions."The group does not keep public records and holds private meetings, so little information can be obtained about what it does.California Sen. Dianne Feinstein co-chairs the group with Rubio, and her spokesman, Tom Mentzer, told the newspaper that the group met three times with State Department officials in July 2013, March 2014 and April 2014, where arms control, North Korea and Iran were discussed. A meeting was planned for October 2013, but was cancelled by the government shutdown.Several members of the group still receive reimbursement for staff expenses: South Carolina Republican Sen. Lindsey Graham, Mississippi Republican Sen. Thad Cochran, Alabama Republican Sen. Jeff Sessions and New Jersey Democrat Robert Menendez each get $60,000 a year. Minority Leader Harry Reid, a Nevada Democrat gets $100,000 a year.