Biden's State of the Union may not help potential 2024 election bid against Trump, experts say

President Joe Biden's second State of the Union address played well with viewers, and may have helped him tee up a bid for reelection in 2024 — but it might not make a lasting impact on his hopes for a second term, experts said.

In his speech to Congress Tuesday night, Biden issued an appeal for political unity while touting his legislative achievements and taking credit for some recent improvements to the U.S. economy. He also sketched a broad outline of his policy goals for his next two years in the White House, including a new minimum tax on billionaires and a beefed-up tax on corporate stock buybacks.

Now halfway through his term, Biden called on the newly divided Congress to help him "finish the job" — a phrase that could lend itself to a reelection campaign — in part by building on his legislative accomplishments, such as expanding a $35 cap on the price of insulin.

"These and other features of the president's speech signaled an important part of his reelection strategy — increasing Democrats' share of the working-class vote, which fell to historically low levels during the 2016 and 2020 elections," William Galston, a senior fellow at the Brookings Institution, said in a blog post Wednesday morning.

"He clearly believes that his party's weakness among these voters reflects economic rather than cultural issues. Many analysts disagree with him, and we won't know who's right until November of 2024," Galston said.

Biden has yet to confirm his plans for the next election cycle. The White House has said Biden intends to run again, and news outlets report he's expected to make a decision soon.

"I'm not sure if Biden's speech will help him to win the election in 2024, but he certainly tried to make a case for why he should run," said Jennifer Mercieca, an American political rhetoric historian and professor at Texas A&M University, in an email to CNBC.

"Someone watching the speech could conclude that Biden should be given more time to finish his ambitious plan to rebuild America," she said.

The president also scored points by responding to his Republican hecklers with some rhetorical sleight of hand. When Biden accused some members of the new GOP House majority of proposing cuts to Medicare and Social Security funds, the Republican half of the chamber immediately erupted in a swell of boos.

"OK, folks, as we all apparently agree, Social Security and Medicare is off the books now, right?" Biden replied.

It was "a rhetorically savvy power move," Mercieca said. She compared it to how former President Thomas Jefferson took on his political opponents in his first inaugural address: "Like Jefferson, Biden encouraged debate and difference of opinion, while also strategically positioning the Republicans who disagree with him as wrong."

The exchange became an instant highlight of the address, which viewers mostly reviewed positively: 72% of Americans who watched the speech had a positive reaction, including 34% who viewed it very positively, according to a CNN poll conducted by SSRS. The poll, conducted via text message from 552 respondents, has a margin of error of 5.7 percentage points.

CNN noted, however, that presidential speeches to Congress typically get high marks from viewers. And the latest poll showed that fewer respondents had a "very positive" reaction to this year's address when compared with a survey taken right after Biden's previous State of the Union speech.

It's also hardly guaranteed if the speech will make a dent in the major obstacles that have dogged the Biden presidency, including underwater approval ratings and a perception from voters that he hasn't accomplished much in office, according to a new Washington Post-ABC News poll.

What's more, the 80-year-old Biden hasn't been able to tamp down on widespread concerns about his age and fitness for the job.

If he runs again and wins, Biden will be 82 years old by the time he is sworn in for a second term, making him by far the oldest president to serve in the office.

That's a major factor for Democrats considering whether to back Biden in the next election cycle, according to a recent survey from the Associated Press-NORC Center for Public Affairs Research. Just 37% of Democrats in that poll said they wanted Biden to seek a second term — a sharp decline from before the midterm elections just a few months earlier. The survey of 1,068 adults had a margin of sampling error of 4.2 percentage points.

Mercieca doubts there's much Biden could have done to temper concerns about his age. "Those concerns are as much about the future as they are about the present," she said. "People who might not be worried about his age and performance now might still be worried about what his age and performance will be like in a few years."

At the very least, Biden's performance Tuesday night didn't make things worse. "He delivered his speech forcefully if not flawlessly, adding no new fuel to questions about his fitness to serve a second term," Galston said.

He doesn't have much longer to mull a decision. His opponent from the 2020 election, former President Donald Trump, has technically been on the 2024 campaign trail for months, though he has done little in-person campaigning.

More contenders are expected to file in soon: Nikki Haley, a former U.S. ambassador to the United Nations under Trump, is expected to announce her campaign next Wednesday and head to the key primary state of New Hampshire soon afterward.

Former President Barack Obama, under whom Biden served as vice president, had launched his own reelection bid in April 2011, less than three months after his second State of the Union address.