President Barack Obama will travel to the Hill on Tuesday to discuss the situation in Syria with Senate Democrats, a Senate Democratic aide confirmed Sunday.

The administration has been working in overdrive to build a compelling case to lawmakers for intervention in the war-torn country in the days since announcing the president would seek congressional authorization for military action. The Senate vote for authorization faces a 60-vote threshold, and it’s unclear whether there are enough members in support of intervention to clear that hurdle. Senate Democrats — several of whom have said already they cannot support military action in Syria — could be key in providing Obama at least one chamber of support, especially as House Republicans look poised to defect from an authorization resolution en masse.

A senior Senate Republican aide said Sunday evening that leadership had not yet heard anything from the White House about a potential meeting Tuesday with the GOP.

A rebuff of an authorization resolution in the chamber controlled by his own party would be embarrassing for the president, much like a recent British parliament vote that rejected Prime Minister David Cameron’s request for military engagement. Though Obama likely could move forward with force in some capacity without a congressional vote of confidence, now that he’s asked for it, proceeding without it could be even more politically perilous than had he not asked at all.

That Obama is coming to the Hill himself, after top officials like Secretary of State John Kerry and Secretary of Defense Chuck Hagel made multiple appearances before lawmakers last week — in multiple closed-door, classified briefings and open hearings — shows just how important the White House believes this is and how much they recognize that military engagement of any kind in Syria is a tough sell.