Rubio says mineral deal 'not main topic on agenda' in Ukraine meeting

"The minerals deal is on the table that's continuing to be worked on - it's not part of this conversation, per se," he said, noting that Tuesday's meeting in Jeddah can be considered successful even without securing such an agreement.

"It's certainly a deal the president wants to see done, but it doesn't necessarily have to happen tomorrow," Rubio added. 

Rubio will meet with the delegation in the city of Jeddah around noon local time on Tuesday.

"Both sides need to come to an understanding," he said. "The Russians can't conquer all of Ukraine, and obviously it will be very difficult for Ukraine, in any reasonable time period, to sort of force the Russians back all the way to where they were in 2014. So the only solution to this war is diplomacy and getting them to a table where that's possible.

 "Then we'll have to determine how far they are from the Russian position, which we don't know yet either. And then once you understand where both sides truly are, it gives you a sense of how big the divide is and how hard it's going to be," Rubio explained. "I'm hoping it'll be a positive interaction along those lines."

Steve Witkoff, special envoy to the Middle East who has increasingly been involved with the talks regarding Ukraine and Russia, told Fox News' Dana Perino on "America's Newsroom" Monday morning, that the Trump administration has "gone a long way" to "narrow the differences" when dealing with Moscow and to get it to the negotiating table - though he did not go into detail. 

"The pause in aid broadly is something I hope we can resolve," Rubio said. "I think what happens tomorrow will be key to that."

Rubio also said that Russia will see its own consequences if it doesn't agree to negotiate on ending the war in Ukraine, including additional sanctions. 

"It should be clear to everyone that the United States has tools available to also impose costs on the Russian side of this equation," Rubio said. "But we hope it doesn't come to that. 

"What we're hoping is that both sides realize that this is not a conflict that can end by military means," he added.