Biden's shaky debate panics Democrats, Republicans celebrate Trump: ANALYSIS

President Joe Biden's decision to debate former President Donald Trump early on was widely perceived as an effort to change the narrative in a race dominated by concerns over his age. His performance Thursday instead only amplified those worries.

"Obviously the gamble did not pay off," said one Democratic source familiar with the Biden campaign's strategy.

Biden's responses, delivered in a raspy voice his campaign attributed to a cold (but only after the debate was well underway) were pockmarked by meandering commentary on his and Trump's policies. At one point early on in the debate, Biden paused for several seconds during a zigzagging remark about what the country could do with the money accrued from higher taxes on the wealthiest Americans.

"We'd be able to help make sure that all those things we need to do, child care, elder care, making sure that we continue to strengthen our health care system. Making sure that we’re able to make every single solitary person eligible for what I’ve been able to do with the -- with the COVID, excuse me -- dealing with everything we have to do with, look … we finally beat Medicare," Biden said, seemingly losing his train of thought.

Trump was also able to pounce when the president similarly trailed off at the end of an answer on a question about immigration.

"I really don't know what he said at the end of that sentence. I don't think he knows what he said, either," Trump said.

Biden appeared to pick up steam as time went on and was able to mix it up more with Trump, including calling him a "sucker" and "loser."

"He has no idea what the hell he's talking about," Biden said of Trump at another point.

But Democrats who spoke to ABC News said the panic was on -- even sparking talk about whether Biden should remain on the ticket.

"I have eyes and ears … so bad," one Democratic strategist said when asked about what they thought of Biden's performance.

"There is no spinning tonight's showing by Biden. It wasn't bad. It was a disaster," added a Democratic pollster, who, like other Democrats, spoke anonymously about the debate.

When asked if the person thought Biden's poor showing would spark chatter about replacing the president on the 2024 ticket at this summer's Democratic convention, the pollster replied, "it better."

The worries are particularly potent given longstanding concerns over Biden's age.

At 81, he is the oldest president in history, and Republicans have made political hay of his halting gait and verbal gaffes to pound away at an argument that Biden is unfit for office.

Polls have shown that many voters share concerns about Biden's fitness for office, even after the State of the Union in March, where Biden delivered a forceful defense of his record in a speech that Democrats hoped would put voter worries to bed.

Democratic operatives behind the scenes likely have blisters over the amount of handwringing they've privately expressed about how much the Republican attacks appear to be resonating. A New York Times/Siena College poll conducted from June 20 to 25 found that 16% of registered voters said that Trump's age "is such a problem that he is not capable of handling the job of president," while 45% said the same about Biden, including 15% of Democrats.

And while Trump is only three years the president's junior, and similarly makes factual errors on the trail, including mixing up names, surveys show trepidation about his fitness is less widespread.

The former president repeated some of his bombastic rhetoric on stage Thursday, exaggerating economic statistics during his term, repeating claims that he's being persecuted because he's running for president, declining to unequivocally say he'd accept the election results and at one time attacking Biden's son Hunter, who was recently convicted on felony gun charges.

However, Democrats conceded that Biden's halting performance would be the major takeaway from the debate.

"Trump was dislikeable and delusional, but Biden fared worse. The age question whispers in Democratic circles will become louder and more urgent," one Democratic operative said.

Another senior Democratic strategist said Biden "had a bad performance in the face of a torrent of lies and attacks from Trump" and that the debate could spark talks about a brokered convention in August, though that replacing Biden on the ticket would be more difficult than many think.

It's unclear how permanent any damage from the debate lasts. Past clashes haven't single-handedly sunk a president's reelection hopes, and it's possible Biden recovers in the over four months between Thursday and Election Day.

But optimism was hard to find among Democrats.

"I don't think it blows over," said the source familiar with the Biden campaign's strategy.

The Democratic spin mostly focused on Trump's performance rather than Biden's, noting that the president did have actual answers on policy issues, even if he stumbled.

Biden "started wobbly because of the cold but closed strong," said Biden bundler Tim Lim. "Joe Biden gave actual answers and solutions while Trump sounded like a deranged liar."

A Biden adviser added that the president "is the only person who has ever beaten Donald Trump. He will do it again."

Biden himself said he thought he "did well," noting that "it's hard to debate a liar."

But Republicans weren't buying it, crowing of victory just minutes into the debate.

After Biden's seconds-long fumble early in the head-to-head, Bryan Lanza, a former Trump campaign aide who remains in touch with the current team, texted ABC News, "Game over!!!"

"Tonight, President Trump delivered the greatest debate performance and victory in history to the largest voter audience in history, making clear exactly how he will improve the lives of every American," top Trump campaign hands Chris LaCivita and Susie Wiles said in a statement before the event even formally concluded. "Joe Biden on the other hand showed exactly why he deserves to be fired."