US President Joe Biden's debate performance has caused a stir among his own party which has begun questioning whether he should be replaced on the ballot before elections, CNN reported. 

A top White House and campaign official for former president Barack Obama said: "There is a sense of shock at how he came out at the beginning of this debate. How his voice sounded. He seemed a little disoriented." 

"There are going to be discussions about whether he should continue," David Axelrod said on CNN. 

Campaign and party officials noted Biden's rubuke to Trump on January 6 attack as a moment where he hit his stride. They also noted his comments on climate change, arguing that he improved as the time passed.  

Vice President Kamala Harris said that Biden made a "slow start" to the presidential debate. 

A hoarse-sounding Biden stumbled over his words on several occasions during the debate's first half-hour, but he found his footing at the halfway mark. 

However, Biden still has support from Democratic officials as they continue to rally around him publicly and it would be nearly impossible to replace him unless he chooses to do so himself.

And currently, there is no known and serious effort to push Biden off the top of the presidential ticket. 

However, according to CNN, Biden would have to step aside if Democrats were to pick another nominee and the nomination would be decided on the floor if he did withdraw. 

An operative, who worked on campaigns for over a decade, said: "It’s hard to argue that Biden should be our nominee." 

Democrats were even sharing opinions on who might be Biden's replacement. One of them even said: "If I was Gavin (Newsom) or Gretchen (Whitmer), I’d be making calls tonight."

But Newsom said that he would "never turn" his back on Biden.

“Disaster,” one lawmaker told CNN. “Trump is coming off as reasonable even if he’s lying 60 miles per hour. Biden is unintelligible.”

“I think Joe is doing better than he did in the first 15 minutes, and Trump is just lying his way through the debate. But I wish Joe was a lot stronger punching back,” one lawmaker said midway through the debate.

They also question why the president missed opportunities to slam Trump's comments, especially regarding the abortion issue.