President Biden is intensifying his campaign efforts as he looks toward November, planning a series of speeches that aides said on Wednesday would cast the stakes of the coming election as the endurance of American democracy itself.

Even before a single vote is cast in the Republican Party’s nominating race, Mr. Biden and his team are treating former President Donald J. Trump as their de facto opponent in the general election. They’re seeking to frame the contest not as a traditional referendum on the incumbent president and his governance of the nation, but as an existential battle to save the country from a dangerous opponent.

With the calendar flipped to 2024, Mr. Biden is making a notable escalation of his re-election campaign with an address planned at Valley Forge in Pennsylvania on Saturday, the anniversary of the Jan. 6, 2021, Capitol riot by a pro-Trump mob.

The location, where George Washington commanded troops during the Revolutionary War, is intended to draw a sharp contrast between Washington, who voluntarily ceded power after serving as the nation’s first president, and Mr. Trump, who refuses to accept the results of the 2020 race. On Monday, Mr. Biden will appear in Charleston, S.C., at Emanuel African Methodist Episcopal Church, a historically Black church where a white supremacist killed nine parishioners in 2015. The venue embodies the country’s current fight against political violence and white supremacy, his campaign said.