Texas Attorney General Ken Paxton is working to unite Republicans behind his Senate bid after defeating longtime incumbent Sen. John Cornyn, R-Texas, in the GOP primary, but some of the party's biggest donors remain reluctant to back him despite growing concerns about Democrat James Talarico.

According to The Wall Street Journal, several major Republican contributors who supported Cornyn have been slow to embrace Paxton, citing his legal battles, ethics controversies, and history of taking on corporate interests.

Even so, many now view the race as too important to ignore with Republicans defending their Senate majority.

Billionaire businessman Bob Rowling counted among them.

After contributing more than $750,000 to Cornyn-aligned groups, Rowling initially refused to help Paxton's campaign. But after a personal call from Sen. Ted Cruz, R-Texas, he agreed to meet with the Texas attorney general.

Rowling said Cruz handled most of the conversation while Paxton was gracious during the meeting.

Since then, Rowling said he has become increasingly troubled by Talarico's past comments on gender issues and border security, as well as the Democrat's sizable fundraising edge.

Although he has not yet written a check, Rowling said he now plans to make a six-figure contribution.

"It's a binary choice," he told the Journal.

Resistance to Paxton reportedly extends beyond Rowling.

After Paxton secured the nomination, donors tied to one major Republican fundraising organization reportedly asked that their money not be directed to his campaign because his office had sued many of them.

Still, Paxton's campaign says it is building momentum.

Campaign finance reports released Wednesday show Talarico's committees hold $23.3 million in cash, compared with $6.9 million for Paxton.

Paxton's campaign previously announced it raised just over $9 million during the second quarter after clinching the GOP nomination.

"For being the nominee for just 30 days, we feel very confident in our fundraising," Paxton consultant Nick Maddux said.

Among Paxton's recent six-figure donors are Dallas Cowboys owner Jerry Jones, the founder of Curves fitness centers, and the wife of a CEO who was convicted of fraud before receiving a pardon from President Donald Trump.

Not every Republican donor is getting on board, however.

Billionaire Ken Griffin reportedly has no plans to support Paxton, while Texas billionaire Ross Perot Jr. said he will direct his donations where GOP leaders believe they are needed most.

"All the big money is going into the party," Perot said.

Maddux also defended the campaign's fundraising approach to the Journal, telling the outlet it doesn't "make a practice of soliciting the people Ken sues — that would be uncouth."

With control of the Senate on the line, many Republicans are now looking to Trump and the Trump-backed MAGA Inc. super PAC to play a larger role in helping consolidate GOP support behind Paxton ahead of November.