President Joe Biden’s presence on the campaign trail failed to resonate with voters, GOP strategists say, and ended up hurting his Democratic colleagues in what Biden himself has said is "one of the most important elections in our lifetime."

Biden played it safe on the campaign trail over the past week as he visited mostly Democrat-heavy areas, but he already did damage to Democratic candidates with several appearances that failed to talk about issues that voters care about. GOP strategists said the shift in polling data toward Republicans in recent weeks can be attributed, at least in part, to Biden’s lackluster performance on the campaign trail.

Brendan Steinhauser, a consultant for GOP candidates, said Biden failed to create a message that can appeal to moderate voters.

"I think his message is tone-deaf and out of touch, especially with working-class voters and independents," Steinhauser told Fox News Digital. "He’s still relatively popular with the Democratic base, but that’s it. With independent and swing voters, he’s a liability not an asset."

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Republican pollster Dave Winston said Biden’s most significant shortcoming is his inability to deliver a message on the economy, which will hurt Democrats this year.

"Part of the challenge has been that Biden has not effectively addressed the No. 1 issue for voters, which is inflation," Winston told Fox News Digital. "My sense is that things have improved for Republicans over the past couple of weeks based on the content both sides are discussing."

Richard Painter, an ethics lawyer who worked in the George W. Bush administration, said Biden’s biggest mistake on the campaign trail was his inability to "keep the facts straight." He said Biden’s working-class image may not hold up in Pennsylvania due to his lifelong career in the nation’s capital.

"He talks like a Democrat, but he’s a little too close to the powerful elites for Pennsylvania," Painter told Fox News Digital. "One of his problems is that once he got into power, all of the people with money wanted to get closer."

Democratic strategists said using Biden mostly in blue states is a deliberate strategy. Kevin Walling, a campaign strategist and former Biden 2020 campaign surrogate, said that plan is similar to Republican candidates' selective use of whether to campaign with Trump.

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"President Biden is popular when it comes to Democrats in Philadelphia and New York and will absolutely be helpful to [New York] Gov. [Kathy] Hochul and [Pennsylvania] Lt. Gov. [John] Fetterman in terms of turning out Democrats in the lead-up to Tuesday," Walling told Fox News Digital.

But most analysts agree that Biden's many gaffes on the campaign trail hurt Democrats. Biden mistakenly called General Motor CEO Mary Barra "Amy Barrett;" he claimed that he spoke to the creator of insulin, who died before he was born; he referred to Rep. Debbie Wasserman Schultz, D-Fla., as a "friend in the Senate;" and he repeated his debunked claim that he traveled 17,000 miles with Chinese President Xi Jinping.

In his final campaign event Monday night, Biden appeared to forget the name of the Maryland candidate he was there to support. 

"And, of course, you got that next governor. What’s his name? Wes… Wes…," Biden said to the audience as they held up "Wes Moore" signs. 

"Wes Moore!" Biden eventually said. "The guy’s the real deal, man." 

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The most significant blunder from Biden, according to several operatives, was his comments on oil. When confronted by a climate activist, the president said there will be "no more drilling" and claimed that "I haven't formed any new drilling." The White House, meanwhile, boasted it has issued 9,000 new drilling permits to counter high gas prices.

The oil comments pleased progressives, but even some Democrats worry it may scare away moderate voters who prioritize the economy. Mark Penn, a Democratic strategist, said Biden’s comments on oil were a "huge mistake" and that Biden’s presence on the campaign trail was in many cases unnecessary.

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"I think nationalizing the race is the wrong thing to do," Penn told Fox News Digital. "The more you bring national figures, including Biden, into the picture, the more you make the race about national priorities instead of the quality of the local candidates. And on inflation, crime and immigration, the Republicans have a wide edge."

Biden largely campaigned in deep-blue states such as New York, California and Illinois, but he also campaigned in one especially tight and crucial race: the U.S. Senate race in Pennsylvania. Former President Barack Obama joined Biden on Sunday in an event with Democratic candidate Fetterman, whose lead in the polls has shrunk in recent weeks against Republican candidate Mehmet Oz. That race could determine the Senate majority.