The Florida Republican's spokesman Alex Conant explained that Rubio was missing the briefings after attending a classified Intelligence Committee session on the attacks on Tuesday. As a member of that committee, he would have access to information not afforded to all senators.
Still, the Democratic National Committee sent out an email blast assailing the presidential candidate for skipping out on Wednesday's briefing to attend a fundraiser.
"While the rest of the world is focused on the terror attacks in Paris, Rubio is skipping critical briefings on national security to focus on high-dollar fundraisers," DNC spokeswoman Christina Freundlich said in a statement. "He excuses his poor voting record by saying the votes he misses don't matter, but it's especially galling when he's missing national security briefings in order to attend ritzy West Coast fundraisers."
Rubio's opponents on both sides of the aisle have tried to paint him as an absentee senator for missing the most votes this year of the senator candidates, but he has responded that he makes sure to attend important votes.
He has also turned his frustration with Congress into a campaign message, saying he is missing votes to run for president to effect real change.
The DNC email specifically hit Rubio for missing a closed briefing of the Foreign Relations Committee on the attacks on Wednesday morning.
That meeting was largely focused on the refugee situation, with witnesses from the State Department, Department of Homeland Security and Office of the Director of National Intelligence.
The candidate will be attending an evening fundraiser in Newport Beach, California, that starts at $1,000 per person.
Rubio is the only candidate in the race who serves on the Senate Intelligence Committee, and as such would be the only one with access to the classified information the committee is briefed on regularly.
Kentucky Sen. Rand Paul, Rubio's presidential opponent, also serves on Foreign Relations and was at Wednesday morning's session, his office confirmed. He will also be at the Wednesday evening briefing.
None of the Senate offices of the other senators running for president, including Sens. Lindsey Graham, R-S.C.; Ted Cruz, R-Texas; and Bernie Sanders, I-Vermont, immediately responded to a CNN inquiry about whether the lawmakers would be attending the all-Senate briefing Wednesday evening.