Six weeks after he ended his re-election campaign amid rising calls from his own party to drop out of the race, President Biden returns to the campaign trail for the first time on Monday.

It will be the first of a "robust" schedule of campaign appearances by the president on behalf of Vice President Kamala Harris over the next two months, a White House official tells Fox News.

"President Biden will be leaning in heavily over the next several months to finish the job," White House communications director Ben LaBolt said.

Biden will team up with Harris, whom he endorsed and who replaced him atop the Democrats' 2024 ticket, at a Labor Day event in Pittsburgh, a union stronghold and the biggest city in the western half of the key battleground state of Pennsylvania.

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Biden, Jill Biden and Harris on DNC stage

President Biden stands with Democratic presidential nominee Vice President Kamala Harris, left, and first lady Jill Biden during the first day of the Democratic National Convention on Monday, Aug. 19, 2024 in Chicago. (AP Photo/Jacquelyn Martin)

The Harris campaign says that the vice president is expected to say that U.S. Steel [the Pittsburgh-based corporation which is the nation's second-biggest steel producer] should remain domestically owned and operated and "stress her commitment to always have the backs of American steel workers."

The stop is part of a full court press by the Harris campaign on Labor Day in some of the seven key swing states that will likely determine the winner of the vice president's election showdown with former President Donald Trump, the Republican nominee.

LaBolt said that going forward, Biden will be "campaigning to elect Vice President Harris and Governor Walz and spending time with core constituencies with whom he has a long relationship, continuing to deploy investments in manufacturing, infrastructure, and emerging industries like clean energy, and strengthening our alliances on the world stage."

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Biden's disastrous performance against Trump in their late June debate turned up the volume on existing concerns from Americans that the 81-year-old president would have the physical and mental stamina to handle another four years in the White House. It also sparked a rising chorus of calls from top Democratic Party allies and elected officials for Biden to drop out of the race, which he did on July 21.

Biden was showered with chants of "thank you, Joe" as he teamed up with Harris on Aug. 15 in Largo, Maryland, for their first joint appearance since his departure from the 2024 race. While it was billed as an official White House event to announce that the federal government had negotiated lower prescription drug prices with pharmaceutical companies that will likely save Americans billions of dollars, the gathering had the feel of a political rally.

biden on stage flag

President Biden and Democratic presidential nominee Vice President Kamala Harris arrive to speak about the administration's efforts to lower costs during an event at Prince George's Community College in Largo, Maryland, on Thursday, Aug. 15, 2024. (AP Photo/Susan Walsh)

Four days later, Biden was praised and applauded on a much larger scale, as he gave the headliner address on the first night of the Democratic National Convention in Chicago. It was a remarkable moment for a president, who weeks earlier was essentially pushed out of the race by his own party.

Harris, in a surprise appearance, joined her boss at the podium inside Chicago's United Center following his speech.

Since replacing Biden as the party's standard-bearer, Harris has enjoyed a rise in the polls and a surge in fundraising as part of the wave of momentum and energy she continues to ride.

Biden remains popular with many in the base of his party, and the president has a long history of campaigning on behalf of fellow Democrats. He was the most requested Democratic Party surrogate during the 2018 midterm elections when the party reclaimed control of the House.

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A source in Biden's political orbit told Fox News that the president continues to have "a lot of political appeal and juice with some of the key voters that we’re going to need to win in November."

The strategist, who asked to remain anonymous to speak more freely, told Fox News that "the stakes of the election are what got him to run for re-election. It’s what he thinks about every single day… Just because it’s not his name on the ticket doesn’t mean that he doesn’t care just as much about winning this election. That’s why you’ll see him fighting, because all the stuff that he said when he was running he still believes."

"Going to Pittsburgh, talking about the economy and reaching the voters that he has strength with, I think you’ll see him do that a lot," the source added.

The president said this weekend that his stop in Pittsburgh, a city he has frequently visited over the years, would be the first of many campaign trail appearances between now and November's election.

President Biden hits the campaign trail on behalf of Vice President Kamala Harris

President Biden speaks to reporters outside of St. Edmond's Roman Catholic Church in Rehoboth Beach, Delaware, after attending a mass on Saturday, Aug. 31, 2024. (AP Photo/Manuel Balce Ceneta)

"I am on the road from there on," the president told reporters on Saturday.

However, there are some risks with putting Biden back on the campaign trail. While his approval ratings have slightly edged up since he dropped his re-election bid, they remain well underwater. And many Americans blame Biden and his administration for the high prices for gas and groceries they've been paying the past couple of years.

Additionally, while Harris repeatedly works to portray herself as a leader who will chart a "new path forward," Biden is a reminder to voters of the present and the past.

"Kamala Harris is spending Labor Day campaigning with her partner-in-crime Joe Biden desperately trying to gaslight the American people. Meanwhile, this Labor Day the American people are working harder than ever to afford gas, groceries, and rent because Kamala Harris broke our economy and is proud of it," Trump campaign spokesperson Karoline Leavitt argued in a statement.

Sources in the Harris campaign confirm that going forward the president and vice president will campaign together at times – and that Biden will focus on his native state of Pennsylvania, as well as Michigan and Wisconsin, the two other Rust Belt states that make up the Democrats' so-called "Blue Wall."

The party reliably won all three states for a quarter-century before Trump narrowly captured them in the 2016 election to win the White House.

Four years later, in 2020, Biden carried all three states by razor-thin margins to put them back in the Democrats' column, as he defeated Trump.

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Biden heads to Wisconsin and Michigan later this week to tout the administration’s efforts to lower costs, for official events that will likely pack a political punch, thanks to the president's continued appeal with White, working-class voters and union members.

LaBolt said that the president's schedule going forward "will be robust and he plans to leave it all on the field in securing as much progress as possible for hardworking Americans, be that through implementation or legislative action."

Get the latest updates from the 2024 campaign trail, exclusive interviews and more at our Fox News Digital election hub.