Two big name Democratic senators -- and a Republican household name -- weighed in on Sunday about the possibility of challenging President Trump in the 2020 general election.

While neither Sens. Sherrod Brown, D-Ohio, nor Amy Klobuchar, D-Minn., said they would be running for the White House in 2020, both Democratic lawmakers also didn’t rule out the possibility when asked Sunday during appearances on ABC’s “This Week.”

“I haven't done any of those things to prepare,” said Brown, who recently won re-election for his seat representing Ohio in the Senate. “But we're seriously thinking about it with family and friends and allies.”

Klobuchar, who made national headlines for her tough questioning of Supreme Court Justice Brett Kavanaugh during his controversial confirmation hearing, was even less open about the speculation that she would challenge Trump in two years.

“People are talking to me about this I think, in part, because I have worked really hard to go not just where it's comfortable but where it's uncomfortable," she said.

Klobuchar was just re-elected by a large margin to her third term representing Minnesota in the Senate and that – paired with her national prominence -- has many people speculating that she could become a presidential favorite among Democrats.

“She’s viable, she is a centrist, and I’m sure that folks that matter look at that possibility and can certainly envision that in a general election against Trump she would look fantastic,” Lou Frillman, a Minneapolis businessman and prominent Democratic donor, recently told the Star Tribune newspaper.

It’s not just big-dollar donors who are pushing for Klobuchar to run for president, but also former Democratic Party heavyweights.

“She got that engine that Humphrey had,” former Vice President Walter Mondale told the Minnesota newspaper, in reference to another Minnesota politician who ran nationally, Hubert Humphrey, who also served as vice president. “They never get tired — they just go and go and go.”

For her part, however, Klobuchar said she was not ready to make any decisions about a 2020 presidential run just yet.

“I have no announcement for you on your show,” she said on Sunday.

While no candidates have officially said they are running for the presidency yet, speculation is that the Democratic field looking to take on Trump in the general election will be deep. Former Vice President Joe Biden is seen as the presumptive frontrunner, but everyone from 2016’s surprise challenger, Vermont Sen. Bernie Sanders, to current Democratic cause célèbre, Texas Rep. Beto O’Rourke, are being discussed.

On the Republican-side, the incumbent Trump might face a rare challenge from someone in his own party.

Outgoing Ohio Gov. John Kasich said on “This Week” on Sunday that he was not ruling out the possibility of taking on Trump.

"We need different leadership, there isn't a question about it,” Kasich said. “I'm worried about our country in the long term.”

Kasich, a moderate Republican who made a run for the presidency in 2016, added that he did not know when he would make a decision whether or not to run.

“I'm not being coy,” he said. “I'm not doing this for a game, this is really serious for me.”

And on the possibility of a joint, bipartisan ticket with a Democrat – particularly one like Brown – Kasich said it probably wouldn’t work out.

“You can't both be from same state, so that's out of the question,” he said.