Shapiro's 2022 campaign for governor for Pennsylvania statewide races.

In that race, Shapiro raised $1 million from billionaire , who has spent millions backing candidates who support gun safety reforms, according to campaign finance records. He also raised an additional $3 million from longtime Democratic donor Jennifer Duda, who lives in California.

Bloomberg has yet to publicly endorse Harris. But some of the vice president's allies are planning to approach the former New York mayor for his support, according to a person familiar with the matter.

Bloomberg has a net worth of over $100 billion, according to . A spokesman for Bloomberg did not return a request for comment. Duda did not return emails seeking comment.

Shapiro is one of the more moderate contenders to be Harris' running mate. He a Republican-backed state plan to send $100 million to families for private school tuition and school supplies, according to . The plan was ultimately scrapped.

Shapiro has taken a stance in its 10 month war on Hamas in Gaza, although he has also acknowledged Palestinian suffering. Shapiro is also a for gun reform legislation.

A spokesperson for the governor did not respond to a request for comment from CNBC.

When it comes to fundraising, Kelly has an advantage that most of Harris' potential running mates do not: a record of support from the tech sector.

As Trump makes headway with the traditionally progressive donor class in Silicon Valley — in part by regulations — ' allies in the tech space have been trying to raise money from Silicon Valley donors, too.

As a senator, Kelly has pushed for related investments in Arizona, including around the U.S.-Mexico border. Kelly and fellow Arizona senator Kyrsten Sinema celebrated when it was announced that Arizona-based Amkor Technology Inc. would receive $400 million from the CHIPS and Science Act.

Kelly's 2022 reelection campaign raised almost $90 million, with employees from , , , , and combining to donate over $1.5 million, according to OpenSecrets.

Kelly, though, could have his detractors in the tech sector, too. He introduced a bill last year that would require internet giants to contribute to Federal Communications Commission's universal service fund program, to Broadband Breakfast.

A spokesperson for Kelly did not reply to a request for comment from CNBC.

Though many of Harris' options to be her running have ties to unions, few have allegiances to them stronger than Walz.

Since he first ran for Congress in 2005, Walz has received regular campaign donations from the National Education Association, the International Brotherhood of Electrical Workers and International Brotherhood of Teamsters, according to the campaign finance website Follow The Money.

A career high school teacher and former union member himself, Walz and has been for years for the importance of organized labor.

But Walz could also have a tougher time making inroads with the kinds of donors who are meeting with Shapiro this weekend, or some Silicon Valley and Wall Street Democratic donors who believe organized labor wields too much power in the party's broader coalition.

A spokesperson for Walz did not reply to a request for comment from CNBC.

Ever since Buttigieg ran in the 2020 Democratic primary for president, he's maintained his own national fundraising network. After he dropped out of the race, he launched a political action committee called .

After he was confirmed as transportation secretary, the PAC remained active, and it had over $1 million cash on hand heading into July, according to Federal Election Commission records. His primary campaign for president raised almost $100 million, according to OpenSecrets. He too received donations from those working in tech.

And that network has been a benefit to the Biden campaign, which is now run by Harris, according to a person briefed on the matter.

In 2020, Buttigieg and his allies helped raise at least $12 million for Biden and around $4 million for other Democrats, this person explained. Since May 2023, Buttigieg and his network have helped the campaign raise around $7 million.

Buttigieg's "donors still work together," this person explained. "Any fundraiser Pete does on behalf of the Harris team, they show up (even without being asked) and rally."

A spokesperson for the Transportation Department did not return a request for comment.