Defense Secretary James Mattis and Secretary of State Rex Tillerson will brief a Senate panel Wednesday, Aug. 2 on the prospects for a new authorization for the war against the Islamic State group, CNN reports.

The closed briefing with national security leaders is another step signaling renewed momentum on Capitol Hill for Congress to finally vote on the war.

But there are still significant roadblocks to passing a new Authorization for Use of Military Force to replace the 2001 authorization still being used by the US military to fight IS, al Qaeda and others across the globe.

A small group of lawmakers from both parties have long been pushing for Congress to pass a new authorization for the war against IS, and their effort received a jolt in the arm in June when a House panel voted to repeal the 2001 war authorization, a 60-word broad authorization approved just days after the Sept. 11, 2001 terror attacks.

The amendment to the defense appropriations bill from Rep. Barbara Lee -- a California Democrat who was the only member of Congress to vote against the 2001 AUMF -- would have repealed that authorization while giving Congress eight months to pass a new one.

But her effort was stripped from the underlying defense bill by House Republican leadership when it went to the floor last week, as House Speaker Paul Ryan argued the spending measure was an inappropriate means to debate the war.

The problem with trying to pass a war authorization is twofold: Many lawmakers are still wary of the way that the 2002 vote for the Iraq War was used against Hillary Clinton in both the 2008 and 2016 presidential elections.

In addition, while most lawmakers support a new war authorization to fight IS, there are major disagreements over the details, including whether to allow or restrict US ground troops, the length of time for the authorization and whether to have geographical restrictions.