Democratic strategist James Carville said Sunday it will be "very, very difficult" for Democrats to take back control of the U.S. Senate in 2018, placing the chances at well below 50 percent.

"I think right now most Democrats are trying to focus on the 2018 elections and trying to recruit people and keep incumbents, and, you know, I would say we have a pretty good chance of taking the House back," Carville told New York radio host John Catsimatidis, according to The Hill. "The Senate is very, very difficult."

Democrats need to pick up three seats in 2018 to win back control of the chamber, but they're defending seats in multiple states that President Donald Trump won handily in 2016. Sens. Claire McCaskill (D., Mo.), Joe Donnelly (D., Ind.), Heidi Heitkamp (R., N.D.), and Joe Manchin (D., W. Va.) are among Democrats up for re-election in 2018 who are vulnerable to being defeated by Republican challengers.

The pick-up attempts for Democrats are more difficult, with Republicans mainly defending seats in red states.

"The problem in the Senate is we have a large number of seats we have to hold in states that Donald Trump carried," Carville said. "Indiana, Missouri, you know places like that that we have to hold seats … I would say the chances of the Democrats winning the House back, let's just say it's 50-50 … [The chance of] winning the Senate is substantially less."

Carville added "no one" was in charge of the Democratic Party at the moment. He also said that Republicans were in trouble because of their move to change the health care system, pointing to congressional losses for Bill Clinton and Barack Obama during their administrations when they tackled that reform.