Democrats are quietly expressing concerns about President Biden's upcoming State of the Union speech on Thursday evening, with others remaining hopeful that the president will use the opportunity to quell worries and attacks over his age. 

"We are all nervous," one House Democrat told Axios, citing concerns about the 81-year-old Biden's "ability to speak without blowing things."

Another House Democrat told the outlet that Biden was likely to make mistakes during his speech. 

BIDEN HEADS INTO SOTU WITH DISMAL APPROVAL RATINGS AS HE BATTLES 1 MAJOR ISSUE THAT'S TAKEN CENTER STAGE

Joe Biden split image

Democrats are quietly expressing concerns about President Biden's upcoming State of the Union Speech on Thursday evening, with others remaining hopeful that the president will use the opportunity to assuage concerns about his age. (Getty Images)

"Listen, (Donald) Trump has made rhetorical slips," the lawmaker said. "Biden is going to make rhetoric slips, I think the key is his energy level."

"There's no doubt that he has the vigor [for a second term], but that's being questioned," former House Majority Leader Steny Hoyer, D-Md., said. "He's quick, and he needs to show that."

Democratic strategist Doug Sosnik told Axios that Biden's "delivery" — not just the words of his speech itself — will be critical. "Given concerns about Biden's age, his delivery will be as important as his substance," Sosnik said. 

Other Democrats said they were confident about Biden's performance at one of the most important political events of a president's term, pointing to his spry showing at last year's address.

"He owned the Republicans when they tried to heckle him," Rep. Ted Lieu, D-Calif., said, adding that Biden will do an "outstanding job."  

Last year, chaos erupted briefly in the House chamber when Biden claimed "some Republicans want Medicare and Social Security to sunset."

WHAT PRESIDENT BIDEN NEEDS TO SAY ABOUT HIS AGE AND TRUMP IN HIS STATE OF THE UNION ADDRESS

Members in Congress

The president's speech to the nation comes just weeks after Special Counsel Robert Hur released his report after the monthslong investigation into Biden's improper retention of classified records. (Drew Angerer/Getty Images)

"It's going to be one of the biggest audiences that the president will have this year, so it's a huge opportunity to make the case," Rep. Greg Landsman, D-Ohio, told Axios. 

White House press secretary Karine Jean-Pierre said Tuesday that Biden was "looking forward to... talking about the accomplishments that he's made the last three years and also the vision that he has for this country."

The president's speech to the nation also comes just weeks after Special Counsel Robert Hur released his highly anticipated report following his monthslong investigation into Biden's improper retention of classified records. 

Hur, in his report, described the president as a "sympathetic, well-meaning, elderly man with a poor memory," and did not bring charges against him. 

Biden's campaign did not respond to a request for comment from Fox News Digital. 

Fox News' Brooke Singman contributed to this report. 

CLICK HERE TO GET THE FOX NEWS APP