Content about the election on social media "could be propaganda" for foreign adversaries, officials with the Office of the Director of National Intelligence warned on Monday.

"The American public should know that content that they read online, especially on social media, could be foreign propaganda, even if it appears to be coming from fellow Americans or originating in the United States," an ODNI official said on a conference call with reporters on Monday. "In short, foreign influence actors are getting better at hiding their hand and using Americans to do it."

Russia is still pervasive in this space and remains the biggest threat to the election, according to the officials.

The officials also warned that the influence operators will use the assassination attempt against former President Donald Trump "as part of their narratives portraying the event to fit their broad goals."

-ABC News' Luke Barr

The Democratic National Committee is claiming it has raised $6.5 million in grassroots donations in the 24 hours after President Biden’s endorsement of Vice President Harris on July 21.

The DNC said $1 million was donated in the 5 p.m. hour alone for what they’re claiming is a record for its best online fundraising day of all time.

The DNC is making a significant push in battleground states, investing an additional $15 million into those crucial states this month to fund new field offices, build data infrastructure, mobilize volunteers and strengthen coordinated campaigns.

“Democratic voters, volunteers, and grassroots donors are fired up," chairman Jaime Harrison said in a memo. "We are confident that in our battleground states, Democrats will win up and down the ballot in November."

-ABC News' Gabriella Abdul-Hakim

Kentucky Gov. Andy Beshear spoke on Sunday at the opening of Kamala Harris' campaign office in Forsyth County, Georgia.

The possible VP pick for Harris has been an effective surrogate for the vice president’s White House bid over the weekend, coming to the metro Atlanta event fresh off of a stump in Iowa on Saturday night.

The red-state governor introduced himself to the Southern audience on Sunday while boosting Harris’ candidacy and taking a number of swipes at Trump’s Vice Presidential pick, JD Vance.

"Are you ready to beat Donald Trump? Are you ready to beat JD Vance? Are you ready to elect Kamala Harris president of the United States of America?" Beshear asked the crowd, adding, "Let's win this race,"

"Let me tell you just a bit about myself," Beshear said. "I'm a proud pro-union governor. I'm a proud pro-choice governor. I am a proud pro-public education governor. I am a proud pro-diversity governor and I'm a proud Harris for president governor," he added.

Calling out Vance, Beshear said, "Just let me be clear. JD Vance ain't from Kentucky. He ain't from Appalachia. And he ain't gonna be the vice president of the United States."

-ABC News' Isabella Murray

Former Vice President Al Gore endorsed Vice President Kamala Harris on Sunday.

"As a prosecutor, [Kamala Harris] took on Big Oil companies -- and won. As [VP], she cast the tie-breaking vote to pass the most significant investment in climate solutions in history, the Inflation Reduction Act. That's the kind of climate champion we need in the White House," he wrote on X.

"With so much at stake in this year's election -- from strengthening democracy in the US and abroad, to expanding opportunity for the American people, to accelerating climate action -- I’m proud to endorse Kamala Harris for President," he added.

-ABC News' Oren Oppenheim