Trump will determine if Putin is 'serious about negotiations' to end Ukraine war, Rubio says

Rubio appeared on CBS' "Face the Nation," where host Margaret Brennan asked if he could trust that potential negotiations with Russia would be forthright considering how Putin "likes to use diplomacy as a cover to distract while he continues to wage war."

Rubio added that there is "no better negotiator in American politics" than Trump, saying that the president "will know very quickly whether this is a real thing or whether this is an effort to buy time."

"But I don't want to prejudge that," Rubio said. "I don't want to foreclose the opportunity to end the conflict that's already cost the lives of hundreds of thousands and continues every single day to be increasingly a war of attrition on both sides."

Trump had repeatedly said while on the campaign trail that if he was president in 2022, the war would not have broken out - vowing to end it if re-elected.

Trump spoke to Putin in a phone call on Wednesday, telling reporters that he and Putin would likely meet soon to negotiate a peace deal over Ukraine. Trump later assured Ukrainian President Volodymyr Zelenskyy he also would have a seat at the table. 

"Ultimately, it will reach a point when you are - if it's real negotiations, and we're not there yet - but if that were to happen, Ukraine will have to be involved, because they're the one that were invaded, and the Europeans will have to be involved because they have sanctions on Putin and Russia as well, and they've contributed to this effort."

Rubio emphasized that the phone call between Trump and Putin was only a small step in the process towards opening a negotiation to end the war, and that "we have a long way to go."

"We're just not there yet," he said. "We really aren't, but hopefully we will be, because we'd all like to see this war end."

The Associated Press contributed to this report.