Sen. Kamala Harris' top donors, including those who have contributed or opened their networks to her, are privately acknowledging that if she doesn't perform well on Thursday, she could start losing the support of wealthy financiers.

In discussions with donors and those close to lead financiers, there is a growing consensus that the California lawmaker needs to have a strong outing against the nine other contenders if she wants to maintain an alliance with many big money donors that have donated to multiple campaigns, including hers.

While she only raised $12 million in the second quarter, Harris came into the race being considered by donors both on Wall Street and within other industries as the preferred alternative to former Vice President Joe Biden. Out of all the money she's raised throughout the first half of the year, $14 million, or 56%, came from large individual contributions, according to the nonpartisan Center for Responsive Politics. Many of these types of donors saw her as an up-and-coming star with moderate policy proposals. For some, she's still in their favor.

But for others, the contest in Houston is being considered a pivotal opportunity for Harris to regain the confidence of the money class and solidify her position against Biden after a disappointing second debate.

"The expectation was really high for her. She came out so strong out of the first debate and she kind of cratered," said one senior New York banking executive that has attended numerous Harris events," said one senior New York banking executive that has attended numerous Harris events. "She has to prove to people now that she's still that alternative to Biden. She's going to have a serious problem on her hands if she can't do that."

A person close to one of Harris's bundlers was even more blunt on what donors are looking for from Harris. "Something, anything attention grabbing," this person said, adding donors will "stay away" if she doesn't show up.

One of Harris' financial supporters on Wall Street simply emailed back "to do well," when asked what donors are hoping to see from her on Thursday.

An associate of a Hollywood titan said that donors will be watching very carefully if Harris can repeat her first debate performance before they decide whether to continue to help her. When asked what they're looking for, this person said "The kind of clarity and presence she displayed at the first debate."

After the initial debate, Harris was publicly praised for taking on Biden, which included an attack on his past record working with segregationists while a member of the U.S. Senate. She was criticized for failing to make the same impact months later when she faced Biden again in the second debate and since then, has seen a drop in the polls. She currently trails Biden, Sen. Elizabeth Warren and Sen. Bernie Sanders, according to a Real Clear Politics polling average.

Rufus Gifford, President Barack Obama's former ambassador to Denmark and his reelection campaign finance director, explained that all of the candidates will be looking to make an impact as the third quarter comes to an end.

"I think the next debate is very important for everyone. Especially those still in tier 2 and are looking to break into tier 1," he told CNBC.

A Harris spokesperson did not return a request for comment.

Still, regardless of what happens in Texas, Harris is planning to jump back onto the fundraising trail with a core group of supporters.

The day after the debate, she will remain in Houston for her first of at least two dozen fundraisers that will take place across the country over the course of the next two weeks, according to a private emailed list of upcoming donor events.

The upcoming money making stops include gatherings in New York, Philadelphia, Chicago, Seattle and Los Angeles. The invites show that while in L.A., Harris will be hosted by a slew of Hollywood insiders such as actor Don Cheadle, Executive Vice President of Warner Brothers Julian Petty, high profile attorney Matt Johnson, and film producer Ellen Goldsmith-Vein, along with her husband, Jon Vein.