It seemed like Sen. Bill Nelson was everywhere on Monday.

The third-term Democratic senator from Florida will forever be best known for, during his time in the House, orbiting Earth aboard the space shuttle Columbia.

But on Monday, Nelson’s politics and policy took center stage. He got a high-profile Republican challenger for his re-election bid and he was face-to-face with the Silicon Valley executive at the center of what was one of the biggest stories of the day.

As the ranking Democrat on the Senate Commerce, Science and Transportation Committee, he met with Facebook CEO for Mark Zuckerberg for roughly an hour on the seventh floor of the Hart Office Building.

Nelson said that among the topics that he brought up during his meeting with Zuckerberg was the investigation led by Special Counsel Robert S. Mueller III into Russia’s efforts to interfere in the 2016 election. Nelson made that revelation after being asked about what he would like to see done regarding regulation of Facebook and other social media platforms by the Trump administration.

Watch: Three Democrats Who Own Facebook Shares Will Question Zuckerberg

“First of all, I’d like for Robert Mueller to be able to issue his report unimpeded. Let’s see to what degree these social media were in fact used and how close it comes, and once we know that, then we’ll know a lot better about how to go forward,” Nelson said.

Nelson suggested that some of the joint hearing of the Senate Commerce and Judiciary hearings Tuesday should examine political advertising on Facebook.

“My understanding is that they have a three-pronged effort now to try to go out and determine who are the fake sites that would be generating fake news, and then on sites that appear to be legitimate, to check the veracity through third parties … checking the veracity of the message,” Nelson said. “Is that going to be enough? I don’t know the answer to that, but we better start asking that question.”

Nelson opted to host an announced press conference following his meeting with Zuckerberg, which Commerce Chairman John Thune, R-S.D., opted against.

Nelson’s huddle with reporters came just hours after the formal entry of Florida Republican Gov. Rick Scott into the 2018 Senate race against Nelson, setting up a marquee contest. And the senator did not shy away from responding to press questions about the campaign back home, even as he was focused on social media and personal privacy.

“I don’t care who is an opponent. I always take them seriously, and I run like there is no tomorrow,” Nelson told reporters Monday. “I think that in this case a lot of the differences between the two of us are going to come out in the course of the campaign.”

Inside Elections with Nathan Gonzales rates the race as a Toss-up. 

Mid-afternoon Nelson and Scott came close to a television collision, appearing separately during the same hour on the Fox News Channel, as Nelson was making the rounds to talk about Facebook.

“I think this election will be about how do we fix Washington? how do we change Washington? I think the voters will think we need to send somebody to Washington that has a background of getting something done,” said Scott. “We have a great economy in Florida, but we need a better national economy.”

Scott’s announcement, which came with a video message Monday, was entirely expected.

“Some say as governor I’ve never fit in,” Scott said. “Well that’s true. I never plan to fit in. And I won’t fit in Washington either,” he said, before criticizing Washington for being “full of politicians.”