WASHINGTON – House Republicans pushed ahead Monday with their investigation of the deadly assault on the U.S. diplomatic mission in Benghazi, Libya, last year as President Obama asserted that Republican charges of a cover-up are baseless.

The latest Republican focus is the independent review that slammed the State Department for inadequate security at the installation before the twin nighttime attacks that killed Ambassador Chris Stevens and three other Americans on Sept. 11, 2012.

Rep. Darrell Issa, R-Calif., chairman of the House Oversight and Government Reform Committee, asked the two authors of the investigation — veteran diplomat Thomas Pickering and retired Adm. Mike Mullen, the former chairman of the Joint Chiefs of Staff — to meet privately with committee staff to answer questions about their review. Democrats countered that if Congress wants to talk to them, Issa should hold a full open hearing.

Republicans insist that the Obama administration misled Congress and the American people in the immediate aftermath of the attack, trying to play down an act of terrorism that would reflect poorly on Obama weeks before the 2012 presidential election.

Emails disclosed Friday showed that State Department and other senior administration officials pushed for references to prior warnings and al-Qaida to be deleted from the talking points used by U.N. Ambassador Susan Rice five days after the attack. One email suggested that Congress could use those issues as ammunition against the State Department.

At a White House news conference, Obama dismissed the Republican focus on the talking points as a politically driven “sideshow,” pointing out that he said “act of terror” on Sept. 12 and the talking points assessment was similar to the daily presidential briefing he had received.

He also noted that Matt Olsen, director of the National Counterterrorism Center, told Congress that Benghazi was a terrorist attack with potential links to al-Qaida three days after Rice’s appearance on five Sunday talk shows.

“So if this was some effort on our part to try to downplay what had happened or tamp it down, that would be a pretty odd thing that three days later we end up putting out all the information that in fact has now served as the basis for everybody recognizing that this was a terrorist attack and that it may have included elements that were planned by extremists inside of Libya,” the president said. “Who executes some sort of cover-up or effort to tamp things down for three days?”