Republican presidential candidate Donald Trump's fundraising effort is getting a big boost from veteran Republican donors. (Mark Humphrey/AP)

This post has been updated.

Some of the Republican Party's most influential fundraisers and donors are signing on to an effort to raise as much as $1 billion for Donald Trump and the Republican National Committee, a sign that apprehension about the real estate developer among the party's money class is giving way to active support.

At least six top GOP money players have agreed to serve as vice chairs of the Trump Victory Fund, a joint fundraising committee between Trump's campaign, the RNC and 11 state parties, according to multiple people familiar with the discussions.

The team include figures who served as major financial backers of Trump's past rivals, including New York Jets owner Woody Johnson and former ambassador Mel Sembler, who were top fundraisers for former Florida governor Jeb Bush's campaign and super PAC, respectively. Wisconsin roofing billionaire Diane Hendricks, who put $5 million into a super PAC allied with Wisconsin Gov. Scott Walker, has also come aboard. In addition, the previous three RNC finance chairmen have agreed to serve as vice chairs: Dallas investor Ray Washburne, who had been the national finance chairman for New Jersey Gov. Chris Christie; Ron Weiser, a national co-chair for Sen. John McCain's 2008 presidential campaign and a former ambassador to Slovakia; and Los Angeles venture capitalist Elliott Broidy, who serves on the board of the Republican Jewish Coalition.

The participation of some of the party's best-connected bundlers shows how rapidly opposition to Trump is melting in the donor class. Just a few months ago, Sembler expressed dismay at the thought of Trump as the party's nominee. "I kept telling myself that won't happen, that can't happen. ... I now fear it may happen," he told the Tampa Bay Times in February.

Now he and the rest of the vice chairs, led by Lew Eisenberg, the RNC's finance chairman, will serve as the top tier of the still-forming Trump fundraising structure. The operation is getting a big boost from experienced finance staff at the RNC, as well as Chairman Reince Priebus, who is calling major fundraisers himself to ask them to host events.

Trump is slated to headline his first fundraiser for the effort this evening in Albuquerque. The reception and photo line, which is being hosted by former funeral services company owner Kevin Daniels, requires a $10,000 donation per person.

From there, the presumptive GOP nominee heads to Los Angeles, where a high-dollar fundraiser at the home of investor Thomas Barrack Jr. is expected to generate about $5 million, according to people familiar with the event.

Correction: An earlier version of this story identified Kevin Daniels as the owner of a funeral services company. He has not owned the firm for nearly four years.