(CNN) -- President Barack Obama called on Congress Thursday to fully fund administration requests for additional diplomatic security measures in the wake of the 2012 attack on the U.S. Consulate in Benghazi, Libya.
The requests include increasing the number of Marine guards dispatched to protect facilities around the world, Obama said.
"I am intent on making sure we do everything we can to prevent another tragedy like this from happening," he told reporters Thursday at a joint news conference with Turkish Prime Minister Recep Tayyip Erdogan.
Obama's entreaty to Congress comes amid continuing sharp criticism by many Republicans of the administration's response to the September 11, 2012, attack that killed Ambassador Christopher Stevens and three others.
One of the sharpest critics, U.S. Rep Darrell Issa, the Republican chairman of the House Oversight Committee, has been engaged in a dispute with the co-chairmen of the Accountability Review Board over their report last year on the attack and the U.S. response to it.
Former U.S. Ambassador Thomas Pickering and retired Chairman of the Joint Chiefs of Staff Adm. Mike Mullen wrote to Issa to demand a public hearing to answer Issa's criticisms, according to a letter obtained exclusively by CNN.
"The public deserves to hear your questions and our answers," they wrote.
Pickering and Mullen chaired the Accountability Review Board convened in October by then-Secretary of State Hillary Clinton to investigate the attack.
Their report found "systemic failures and leadership and management deficiencies" at the State Department leading to the attack.
But it also found no evidence of a breach of duty by any U.S. officials related to the incident.
Many Republicans, however, argue that the administration failed to strengthen diplomatic security in Libya despite deteriorating conditions there, failed to adequately to respond to the attack once it was under way and then misled the public about what had happened.
Issa has called the board's review "a failure" and has asked for further investigations into the Obama administration's response during the attack and its aftermath.
The dispute between Issa and the co-chairmen came to a head after neither Pickering nor Mullen attended a May 8 House Oversight Committee hearing on the attacks, sparking a heated back and forth about who was invited and when.
The rhetoric intensified Sunday during a highly contentious joint appearance with Issa and Pickering on NBC's "Meet the Press" in which Issa maintained that the two "refused to come before our committee." Pickering insisted that he was not invited despite expressing a willingness to testify.
Issa also suggested on the program that Pickering and Mullen meet with the committee behind closed doors so as not to create "some sort of stage show."
But the two asserted in their letter that a public hearing is a "more appropriate forum" and accuse Issa of changing his "position on the terms of our appearance."
"Having taken liberal license to call into question the Board's work, it is surprising that you now maintain that members of the committee need a closed-door proceeding before being able to ask 'informed questions' at a public hearing," they write.
Pickering and Mullen assert that since they are not witnesses but rather officials asked to serve on a review board, they should be permitted to testify in public.
"While we understand and respect that your committee has the authority and responsibility to review the Benghazi attacks, we ask that you similarly understand and respect that the Accountability Review Board bore its own authority and responsibility to review Benghazi," they write.
"What the Committee is now proposing is highly unusual in the context of senior officials who are not fact witnesses but instead are reporting their own independent review."
They have suggested a hearing May 28 or June 3.
On Wednesday, the White House released more than 100 pages of e-mails detailing the complex conversations between the CIA, State Department and White House in developing unclassified talking points that were used to underpin the administration's controversial and slow-to-evolve account of the attack.
That account initially focused on an explanation -- later proved untrue -- that the attack stemmed from a spontaneous demonstration over an anti-Muslim film produced in the United States. There had been such a demonstration in Cairo.
The White House and its congressional allies say the initial confusion and conflicting information was a result of the "fog of war," not a deliberate effort to mislead the public about the source of the attacks.
Senior Obama administration officials contend that the e-mails demonstrate the process of developing talking points for members of Congress to use in media interviews was not focused on politics but rather on events.
For instance, some of the e-mails expressed caution about what should be said publicly during an FBI investigation while others centered on the strength of intelligence at the time.
"Collectively, these e-mails make clear that the interagency process, including the White House's interactions, were focused on providing the facts as we knew them based on the best information available at the time and protecting an ongoing investigation," White House spokesman Eric Schultz said Thursday.