Hillary Clinton's digital ads have transitioned to general-election mode.

"There's much more that unites us than divides us" is a message seen in display ads from Ms. Clinton's campaign since the start of May. The concept is one repeated in recent speeches she's given on the campaign trail, and one that speaks directly to the division in the Democratic party as some diehard supporters of Sen. Bernie Sanders claim they will not vote for the former Secretary of State if she wins the party's nomination.

The Hillary Victory Fund, the joint fundraising committee for Clinton's campaign and the Democratic National Committee, has been running digital display ads featuring the unity line throughout the month of May, according to information from digital ad tracking service Moat Pro. One version of the ad focuses on a smiling Ms. Clinton while another pictures her embracing children.

Meanwhile, despite the fact that he continues to campaign hard in California, which holds its delegate-rich primary next week, the Sanders campaign appears to have brought its standard digital display and video display advertising to a halt since the end of May. Moat data does not account for Facebook or Twitter ads, so those still could be running. The Sanders camp, which has spent a significant amount on standard display advertising throughout the primary season, did not respond to a request to comment for this story.

The Clinton and Sanders camps have each purchased over $1 million in TV time in California since the end of May, leading up to the June 7 primary, according to Kantar Media/CMAG data.

"Considering how many on-the-ground appearances he's doing, you'd think digital would be great for amplifying the effect," said Colin Delany, editor of Epolitics.com and a digital strategy consultant for advocacy and political clients on the left.

Mr. Sanders made headlines after attending Game 7 of the NBA playoffs on Monday between the Golden State Warriors and the Oklahoma City Thunder, which propelled the popular California team to the NBA finals. Mr. Delany added that digital advertising would help target key demographic groups of voters who will be important to either Democratic campaign for a win in California.

Ms. Clinton's message of unity works for the current primary race as well as a general election concept that can counteract the divisive messaging from Donald Trump's campaign, said Mr. Delany. "The idea of coming together, of America being made up of groups coming together, that's a very deep idea in the American psyche."

Mr. Trump has become a clear target of the Clinton campaign in ads that have been seen online in recent weeks from The Hillary Victory Fund. "Tell Trump: America is already great," state the display ads, which picture the real estate mogul with a grimace on his face.

As has been the case throughout the election, the Trump camp -- now having no Republican primary opponents remaining -- currently is not doing any standard digital advertising, according to Moat Pro. It remains to be seen whether the campaign will enhance its digital capabilities if Mr. Trump, now the party's presumptive nominee, gets the nod officially.

However, the GOP appears to be preparing for the Trump camp to continue its limited advertising in TV, online and elsewhere. The party last week said it has committed $150 million to digital advertising in the general election intended to support the party nominee.